In early December 2011, Ricardo Sanchez was super excited to start working with Caroline Wozniacki, but the cooperation has already come to an end and all it will be remembered for is Wozniacki's failure to win her first Grand Slam title at the Australian Open and her actual fall to No.4 in the rankings following the quarterfinal loss at the tournament, after reigning the top spot for most of the time since October 2010.

The cause of the split is that the new coach couldn't find his way in the confines of the already established system of Wozniacki and her father Piotr. In simple words, Piotr had his own way of coaching and Ricardo was supposed to adapt to it, rather than to install his way of work. The two systems clashed, the outcome was that Caroline was confused and Piotr asked Ricardo to leave. (photo: © Neal Trousdale)

Going into today's match Wozniacki had a lot on the line, she had a lot of questions to answer, a lot of critics who she wanted to silence by winning this match. Wozniacki's No.1 ranking was on the line, her status as No.1 WTA player was under question, her ability to win a major was what she was seeking answer to when she took the Rod Laver Arena to face Kim Clijsters for a spot in the semifinals. She wanted a revenge, for it was Clijsters who had denied Wozniacki her first major in the 2009 US Open final, it was Clijsters who denied Wozniacki her first year-end Championships when she beat the Dane in the final in 2010, it was Clijsters who dethroned Wozniacki from the top spot for a week in 2011.

Wozniacki had a lot of reasons to be confident when she entered the Rod Laver Arena. There were questions surrounding Clijsters' ankle, which she twisted badly in her previous match, her performance so far at the Aussie Open was cleaner as compared to Clijsters' as per the stats, she had not lost a set while entering into the match, as against Clijsters who lost a set in her previous match to Li Na. Clijsters had never beaten a reigning No.1 at a Grand Slam in her previous five encounters at Grand Slams with the then reigning No.1s. But it all could not help Wozniacki and it all could not stop Clijsters from crushing the world No.1 to book a semifinal spot.

Going into today's match Clijsters was on a mission, since she had already announced that this would be the last Australian Open of her career. She wanted to end it in style, and yes she did it in style to book herself a semifinal spot against the on-fire Victoria Azarenka. She got her first win over a reigning No.1 in a Grand Slam, and did that in authoratative way by defeating Wozniacki in straight sets. What did Clijsters do to emerge as the winner, when the numbers were in Wozniacki's favour? Let us compare the stats of their quarterfinal encounter with the stats of their previous four matches that earned them the quarterfinal spot.

Wozniacki entered the match as the cleaner player, but Clijsters came out of the match as a winner and a cleaner player. Here is a comparison of Wozniacki's stats of the first four matches and her quarterfinal encounter:

Wozniacki's first serve percentage dropped dramatically as compared to her first four matches, as did her winning percentage on those first serves. She entered the match with a positive differential of winners and unforced errors, but she left the match with a whopping negative 13 differential. I think the table speaks in itself as to why Wozniacki lost.

Let us now have a look at Clijsters' stats, how she raised her game when it mattered the most and added to her already established big player match status.

There is a marked difference in the first serve percentage, although the points won on first serve dropped a little, what is most striking is her differential of winners and unforced errors. While entering the match she had a negative differential of 24, but she hit just one more unforced error than her winner to keep her numbers equal and to win this encounter.

Clijsters' break point conversion rate dropped in this match, which might be a problem against Victoria Azarenka when she faces her for a spot in the finals. But for today Clijsters showed why she was world No.1 and why she owns four major titles. Clijsters lives for another day to battle it out with Azarenka for a spot in the championship match, in the last Australian Open of her career.

Additional info: Here you can read the post-match review of the other Tuesday's quarterfinal – Victoria Azarenka vs. Agnieszka Radwanska. (photos: sr_cranks)

There are so many things you plan on doing, but you you never get to complete them. That is what happened with me, when I had planned on making a probability analysis for the Australian Open 2012, it never got complete and then I got heck of busy. Being an audit trainee no doubt has its perks of excessive late sittings and no weekends, but I just could not resist my urge to analyse the Australian Open quarterfinals, using the performance of the quarterfinalists so far in the tournament. I will be using the stats to look into the quarterfinal showing, as to who has a better shot at making the semis. Let's first analyse Kim Clijsters and Caroline Wozniacki.

Kim got her ankle twisted in her fourth round epic battle against Li Na. Wozniacki won't get a better chance than this to avenge her previous losses to the former world No. 1, after all it was Clijsters who denied Wozniacki the taste of her first major when she beat the Dane in the US Open final in 2009.

Wozniacki has yet to lose a set in this tournament, while Clijsters has already lost one to Li, and was on the brink of defeat in straight sets but turned it around to emerge as a winner. Thousand dollar questions are: Will Clijsters' ankle hold to let her complete in the last Australian Open of her career? Will Clijsters have enough in tank to battle past Wozniacki who has no doubt the best defensive skills at the moment?

Clijsters is 2-0 against Wozniacki, but their last meeting at the year-end Championships in 2010 went the distance. Let us have a look at what the numbers say when we see each player's first four matches at the Aussie Open 2012:

Wozniacki has +8% advantage in the first serves, but what is important is that although Wozniacki has higher 1st serve percentage, Clijsters' 1st serve winning percentage is much higher than Wozniacki's, but so are her double faults. Clijsters has been serving 4+ double faults on average in each match so far, which means losing her serve at least once in each match by only double faults.

What is more worrying is Clijsters' ratio of winners and unforced errors. If you look at the number of winners, Wozniacki is not far behind, but if you look at the number of unforced errors Wozniacki comes out as a cleaner one by a huge margin. Clijsters has a differential of negative 24, whereas Wozniacki has a positive differential of 4. Break point conversion rate, receiving points won percentage again go in Wozniacki's favour. The department where Wozniacki lags is the points won at net. While Clijsters has lost only one point out of her 18 net trips (95%), Wozniacki managed to win only 68% of her net trips.

Numbers are in Wozniacki's favour and Clijsters' twisted ankle boosts Wozniacki's chances a lot, however, Clijsters does have a few things on her side as well:

• Clijsters has the ability of lifting her game when really needed, and we have experienced that in the past as well.
• Her head-to-head against Wozniacki is positive.
• Of nine times Kim has played at the Australian Open, she has always won her quarterfinal match when she has made it to the quarterfinals. She made it to the semifinals or better six out of six times she reached the quarters.

My heart says Clijsters will win, as I am a Clijsters fan, but numbers say Wozniacki is the favorite. This makes me remeber Shakira's (if I am not wrong) song, "Hips Don't Lie", "Numbers Don't Lie".. I will say "sometimes, numbers do lie", that is why my heart says Clijsters will book a semifinal spot. What do you see? Who do u think will come out on top?

For a taste of Omair's previous analyses visit the following pages:

• Part 1: Comparison of the five slamless WTA No.1s and the origin of the phenomenon
• Part 2: Hingis and Davenport were just as slamless No.1s as Jankovic, Safina and Wozniacki
• Comparative analysis of Top 10 players and their performance at big tournaments in 2011
• Part 1: Top 10 players in 2011 – how they scored against fellow big opponents
• Part 2: Top 10 players in 2011 – what do their losses suggest?

(photos: © Neal Trousdale)

The fourth round of the Australian Open feautred a rematch of last year's final and the outcome was the same – Kim Clijsters defeated Li Na. The score 4-6 7-6(6) 6-4 took the Belgian to the quarterfinals, but within those numbers hide four match points, a painful ankle injury at 3-3 in the first set and a gruelling fight of both players.

With her foot thickly wrapped and 2-6 in the second set tiebreak, Clijsters started her big comeback by winning six points in a row to take the match to the third set, which she opened with a 4-0 lead. Li then slowly recovered to 5-4 down, but it was Clijsters who closed out the match to her advantage.

After the victory, the Belgian winner of four Grand Slam titles said that it was one of her best comebacks, while the disappointed Li can live off the number of matches she won in January, a great improvement from her horrible second half of 2011. 

Clijsters was the third WTA player to move into the 2012 Australian Open quarterfinals, as Victoria Azarenka and Agnieszka Radwanska eased past their opponent earlier on Sunday. Azarenka beat Iveta Benesova 6-2 6-2, while Radwanska lost just one game per set against Julia Goerges.

Next for Clijsters will be world No.1 Caroline Wozniacki. The Dane reached the quarterfinals by beating Jelena Jankovic, who helped by committing an astonishing number of 50 unforced errors in the encounter. Jankovic did hit more winners than Wozniacki, as is usually the case with Wozniacki's opponents, but nothing could outweigh those errors, which often had no apparent cause.

The final score was 6-0 7-5 and it was the first time in their eight meetings that Wozniacki bageled Jankovic. Besides their often-mentioned status of "slamless No.1", and besides their mainly defensive game style, Wozniacki and Jankovic have something else in common as of late – Ricardo Sanchez, who not so long ago coached Jankovic, is now Wozniacki's coach. (photo: © Neal Trousdale)

Caroline Wozniacki’s love life is booming, at least its online representation suggests that, and her fashion designer Stella McCartney opted for the color of passion for the world No.1’s Australian Open. Wozniacki accessorized the red dress with a heart-shaped Danish flag pendant that her boyfriend Rory McIlroy gave her for Christmas.

Adidas Adizero used a shade of red for their predominantly peach dress worn by Ana Ivanovic, Daniela Hantuchova and Sorana Cirstea.

Serena Williams is wearing a blue Nike dress with wide tank straps and pleated bottom.

The American opened her Australian Open campaign with custom-made headband and sneakers celebrating Black History Month.

Notice the cute small balls adorning the socks!

Petra Kvitova is, as always, wearing a two-piece Nike outfit, style similar to her 2011 apparel.

Maria Sharapova is wearing a white Nike Maria Statement Slam Dress with electric green straps and a black Nike logo.

Fila is now all over the place, well-represented by Kim Clijsters, Svetlana Kuznetsova and the new additions to the family, Jelena Jankovic and Vera Zvonareva.

Defending champion Kim Clijsters is working a black V-neck shirt with lemon accents and the same shirt in white. A simple black skirt is always there.

Svetlana Kuznetsova is dressed similarly, exposing her "Pain doesn’t kill me, I kill the pain" tattoo.

Jelena Jankovic is still in her first month of promoting Fila, after her three-year contract with Anta has expired, and at the Australian Open she's looking great in an orange Center Court dress.

Another new Fila member, Vera Zvonareva, who used to wear K-Swiss, is in the neutral tones. Sweat marks are spoiling the image, though.

Bethanie Mattek Sands is not exciting us this time. Her look is absolutely toned down. In the photo below you can see her teamed up with Lacoste-clad Jarmila Gajdosova, wearing a very regular Under Armour long-sleeve bright yellow shirt and a white skirt. For her singles match in the first round, Bethanie wore a simple green tank.

Mentioning Lacoste, Samantha Stosur left the brand to sign with Asics, but her white Asics dress didn't get much exposure as the home favorite suffered an emotionally-painful upset in the very first round.

Whose Australian Open 2012 style is your favorite? For me, number ones are Ana Ivanovic, Daniela Hantuchova and Sorana Cirstea in the Adidas Adizero dress (Cirstea upset Stosur in it!), because of the daring combination of colors and a signature modern yet simple design of the line. The runner-up position I would award to Serena Williams' look. (photos: Adidas, Tidalist, Slice, Australian Open, Life)

The 2012 has gained its full swing with the Australian Open, and our loyal contributor and reader John Bolan would like to share his predictions of how the Top 10 rankings will look like at the end of the season. Don't forget to share your Top 10 picks in the comments, as John will send the person whose predictions turn out to be the closest to the actual 2012 year-end Top 10 a picture with an autograph of a Top 10 player. Nice incentive!

Once again, it is time to pick the Top 10 players in the order they will finish on December 31, 2012. We have had a few weeks to observe which players have played well this year. Logic, injuries and where the players finished for 2011 are the main criteria used to make these picks.

My pick for number 1 in 2012 is Victoria Azarenka (I also picked Victoria for number 1 in 2011). She squeaked by Maria Sharapova for third place last year, but is definitely a rising young star whose time has come. Maria is my pick for the runner-up spot – number 2. Let’s hope she stays healthy for the remainder of the year.

Three players who have already been injured this year are Kim Clijsters, Serena Williams and Andrea Petkovic. Do we take a chance and put any of them in the Top 10? Kim is my #3 pick and Serena #4. Although Andrea is the most sensational player in women’s tennis, she is seriously injured and will miss months on the tour in 2012.

My #5 pick is Petra Kvitova. Some say she is now the best player, but she will need to prove it.

Three very consistent players from 2011 – Caroline Wozniacki #6, Agnieszka Radwanska #7 and Vera Zvonareva #8 are my next 3 picks. Caroline’s personal life will interfere with her tennis game in 2012. She will lose her #1 ranking after two years in the top spot.

Li Na is anything but consistent. When she is on she is very good. She’s my number 9 pick.

Number 10 is Sabine Lisicki. She is very strong with one of the fastest serves in the WTA. In 2012 she will finally make her goal of a Top 10 player. I was one of a dozen fans to watch her comeback begin on the first day of the Miami tournament last March. She has played great tennis since then.

I doubt many of you will agree with me on these picks! Use the comments and make your picks! The person closest to the actual finish will get one of my autographed pictures of a player who finishes in the Top 10. Good luck!

Reminder: How accurate was John in 2011? Check out his November reflections on his January 2011 choices.

Thank you, John, for contributing with this article and offering to award a Women's Tennis Blog's reader a with valuable autographed WTA picture.

Caroline Wozniacki, Jelena Jankovic, Li Na, Kim Clijsters, Victoria Azarenka and Agnieszka Radwanska all advanced to the fourth round of the Australian Open and only Azarenka lost more than four games in a set.

Wozniacki and Jankovic will meet in the fourth round, after Wozniacki moved on with a commanding victory over Monica Niculescu 6-2 6-2 and Jankovic cruised past Christina McHale 6-2 6-0, playing well in crucial moments and saving ten break points. Even though Jankovic lost her last three meetings with Wozniacki, the Serb said it was in her overall bad period, and now her motivation and confidence are much greater.

A rematch of the last year's final is also awaiting in the fourth round as Clijsters faces Li. Clijsters beat Daniela Hantuchova 6-3 6-2 in her third match of the tournament, while Li advanced when Anabel Medina Garrigues retired with an ankle sprain after only three games. In the 2011 title match Clijsters defeated Li 3-6 6-3 6-3, in what was a positive experience for both players and the two are excited to repeat the challenge.

Victoria Azarenka, who will play Iveta Benesova in the fourth round, faced a fresh first-time WTA titlist Mona Barthel and won the first set against her in just 31 minutes, hitting only three unforced errors. Barthel brought more resistance in the second set, but after four match points Azarenka defeated her 6-2 6-4.

Julia Goerges moved into the second week of a Grand Slam for the first time after overcoming Romina Oprandi 3-6 6-3 6-1, the Italian who upset tenth seed Francesca Schiavone in the second round. Next for Goerges is Agnieszka Radwanska, the 6-2 6-2 winner over Galina Voskoboeva.

The second set of third round matches awaits! (photo: Tidalist)

Top seed Caroline Wozniacki stormed through the first set of her second round match at the Australian Open 6-1 in just 28 minutes, but Georgian Anna Tatishvili had much more hitting to offer. In the second set, which was almost three times longer, the world No.1 found herself trailing 1-4, and at 4-5 she was on the brink of losing the set when Tatishvili had a set point. Wozniacki then evened the score and closed the match quickly to 6-1 7-6(4).
First serve was working exceptionally well for Wozniacki, who hit nine aces in the match and afterwards joked that she felt a little bit like John Isner. Next for the Dane is Monica Niculescu who beat Pauline Parmentier 4-6 6-4 6-1 in the second round.

Kim Clijsters, Li Na, Agnieszka Radwanska and Victoria Azarenka were all express. Clijsters took just 48 minutes to defeat Stephanie Foretz Gacon 6-0 6-1, Li needed 31 minutes per set to get past Olivia Rogowska 6-2 6-2, Radwanska beat Paula Ormaechea 6-3 6-1 in eight minutes over an hour, while Azarenka remained undefeated this season by rolling past Casey Dellacqua 6-1 6-0. (photo: sr_cranks)

Caroline Wozniacki

Still, it was all good for the world No.1 and she brushed aside Anastasia Rodionova of Australia 6-2 6-1. Rodionova made 36 unforced errors, three times more than Wozniacki, and converted zero break opportunities. World No.83 Anna Tatishvili of Georgia will be Wozniacki's opponent in the second round.

Working the Tomato Adidas by Stella McCartney dress, Wozniacki is battling to retain her top ranking this fortnight. If she doesn't manage to reach the fourth round, and seed No.13 Jelena Jankovic is her biggest opponent on that way, Wozniacki will not be No.1 any more.

Additional info: Over the weekend we had two tournament finishes, with Victoria Azarenka and Mona Barthel emerging as titlists, and on Monday at the Australian Open both the players advanced. Sydney champion Azarenka breezed past Heather Watson, while Barthel, who surprised in Hobart by going all the way to the title from qualifying, won the first set against Anne Keothavong 6-0 but then Keothavong retired because of food poisoning. (photo via Adidas)

Hey everyone. The Australian Open is about to start and this year the field seems to be wide open without clear favorites. Also many of the top players are struggling with injuries and Andrea Petkovic already had to withdraw from the event because of a back injury. In this article I want to give you my view on who has the best chances to win the tournament.

I decided to pick out four players who I believe have the biggest chance to win this year’s Australian Open title.

1. PETRA KVITOVA

Petra Kvitova is currently in a close battle with Caroline Wozniacki for the world number 1 ranking. She had her breakthrough winning Wimbledon last year and I think she has very good chances to become the most successful player in 2012.

Her game is big, she played well in the warm up matches to the tournament, and she seems to have the confidence and belief now.

CHECK OUT HOW WELL KVITOVA IS PLAYING IN THIS VIDEO

2. KIM CLIJSTERS

Clijsters is the defending champion and in my opinion always a threat at any Grand Slam. She had a tough second half of the season in 2011, where she did not play much at all because of several injuries.

Having had such a long preparation could be an advantage for her because she is probably in great shape right now. At the warm-up tournament in Brisbane she seemed to be in strong form but had to pull out because of a hip injury. The latest reports are saying that she is practicing at 100% though and therefore I think she is one of the favourites to win the title.

3. SERENA WILLIAMS

As usual it is difficult to assess what kind of form Serena Williams is in for the Australian Open. She has not played much before the tournament but she obviously likes the tournament, having won it five times in the past.

In a recent interview I heard Brad Gilbert, famous coach and expert, talk about how hard Serena was preparing and how well she looked out on the practice courts. An ankle injury forced her to pull out of Brisbane but she has also been seen practicing hard on site in Melbourne. She has not played many tournament matches in a while so it will be crucial for her to get through the first couple of rounds.

If she gets through the first couple of rounds and stays healthy she will definitely be one of the top favourites for the title.

4. MARIA SHARAPOVA

Sharapova also had to pull out of Brisbane due to an ankle injury. Nevertheless she has been seen practicing regularly on-site at the Aussie Open since then and said that she is confident she can play the tournament.

Sharapova played quite well last year. She is working hard and seems very focused on her goal to win another Grand Slam. As usual a lot depends on serve though. If she had time during the off-season to work on it and get her motion a bit more fluid, then she has a good chance at competing for the title at this tournament.

OTHER NOTABLE PLAYERS

Apart from these four, there are many more players with realistic chances to win the title at this year’s Aussie Open. Let’s have a look at some of the other in-form players.

VICTORIA AZARENKA

Azarenka is currently number 3 in the world. So far she has not had much success at the Grand Slams though. She plays well but I am not sure if her game is big enough to beat some of the top players like Kvitova and Williams when they are at their best late in a Grand Slam.

That being said, she has just won the Sydney warm-up event, beating Li Na in the finals, and played excellent tennis. With so many of the top players slightly injured as well, she could have a real chance to go deep into the tournament with her solid game.

CAROLINE WOZNIACKI

Wozniacki is still the number 1 player in the world but as we all know she has not won a Grand Slam yet.

At the end of last year Caroline hired Ricardo Sanchez as her new coach. I think she made a good move in hiring a new coach to try and make a few minor but important changes to her game. It’s really tough to assess what kind of an impact Sanchez will have, but it is definitely a good sign that Caroline hired someone new and is looking to make some changes to her game.

Caroline was also slightly injured in the warm-up event before the Aussie Open. That combined with the uncertainty as to what they are trying to do with her game, I don’t see her in the group of the top favorites to win the tournament.

SAM STOSUR

Sam Stosur is a player that I expect to do really well in 2012. Her game is huge and she also had a breakthrough last year, winning the US Open. She definitely has the game to do well at the tournament but she seems to be quite nervous performing in front of the Australian crowd. She has never gotten past the 4th round at this tournament.

If she can get her nerves under control she should do well though.

LI NA

Li Na was a finalist last year at the Australian Open. She won the French Open last year and then had a tough couple of months later in the year, where she played poorly. Possibly she was not able to handle the publicity that she got back home in China from winning a Grand Slam.

She showed some excellent tennis in the Sydney warm-up tournament though and I think she will show up playing well at the Australian Open.

LI NA WITH A GOOD WIN OVER PETRA KVITOVA IN SYDNEY

THE DRAW

The draw was released on Friday and there are a couple of interesting things to note.

1. Caroline Wozniacki in the top draw is facing some really tough opponents. She could face Jelena Jankovic in the fourth round and either Li Na or Kim Clijsters in the quarterfinals.

2. The second quarter is a bit weaker in my opinion. Here Victoria Azarenka and Agnieszka Radwanska should have the best chances to get through.

3. The third quarter is quite exciting as well with Maria Sharapova, Serena Williams, and Vera Zvonareva in it. Serena is my favorite in this one but Maria has a good chance of getting through as well of course.

4. In the fourth quarter Petra Kvitova is the clear favourite to me. Sam Stosur is in there as well and it will have to be seen how she handles the pressure of playing in front of her home crowd. Ana Ivanovic and Marion Bartoli are two more players that could make it out of this quarter.

Alright guys. So much for my Australian Open Preview. It should be an exciting tournament and please let me know your own thoughts in the comment section below!

Florian Meier runs the website OnlineTennisInstruction.com where he specializes in helping tennis players improve their game with video tennis tips. (photos: © Neal Trousdale)