Now that Maria Sharapova and Ekaterina Makarova have won the bottom-half quarterfinals of the Australian Open, let’s see what numbers have to say about the WTA quarterfinals from the top half of the draw. This is again a contribution of our stats-loving reader Omair, who likes to use mathematics to predict outcomes of tennis matches.
The following preview is based on the performance of the players so far at the 2015 Australian Open.
SERENA WILLIAMS  vs. DOMINIKA CIBULKOVA 
Head-to-head: Serena leads 4-0
- Serena’s serve has been working well when things did not go her way at this tournament. She has hit an average of 11 aces against three double faults so far, which is the highest of any player remaining in the draw.
- Serena has won 72% of her first serves and 50% of her second serve deliveries, which should be good enough to beat Cibulkova on any given day, however, Cibulkova seems to be a woman on a mission.
- Cibulkova proved everyone wrong by emerging through a tough quarter to make the quarterfinals and she did so with some wonderful tennis. She will, however, need to improve on her first serve winning percentage if she wants to get her first win over Serena, as Serena loves to drill down the second serves of her opponents. Cibulkova has won just 66% of her first serves, but a good 52% of her second serves.
- Break points are rare when you are playing Serena Williams, and you have to take them whenever the opportunity arises, otherwise, you are going to rue your chances. Serena has saved 65% of break points faced so far, while she has been broken nine times, compared to Cibulkova’s ten times.
- Both players have a positive winners-to-unforced errors differential. Serena with a +9 on average per match is a little better than Cibulkova’s average of +6 per match. Cibulkova’s forehand was on fire in her previous match. If she brings that firepower into the quarterfinals she will definitely stand a chance.
- Both players have lost two sets so far. Cibulkova lost a set to Flipkens and Azarenka, while Serena lost a set to Svitolina and Muguruza.
Numbers favor the 18-time Grand Slam champion and she is the woman to beat. Cibulkova, however, might have something of her own to say. She is out here to prove that her run to the finals last year was not a fluke and we know what Cibulkova is capable of. She will have to start fast and strong and keep it going till the end. She will have to keep Serena on the run and guessing, if she wants to make it to the semifinals. Is that a lot to ask from Cibulkova, only time will tell.
I am going to go out on a limb and pick Cibulkova to win this match! Everyone else will be picking Serena Williams, and rightfully so, but it is fun to pick an underdog at times.
FUN FACT : Serena Williams is 5-3 in the Australian Open quarterfinals and has won the title every time she has progressed beyond the quarterfinals.
VENUS WILLIAMS  vs MADISON KEYS
Head-to-head: Venus leads 1-0
- Keys has won 74% of her first serves so far at the tournament, Venus has won 71%. Both players have good serves and they will need their serve more in this match-up. The player whose serve is off will definitely be in big trouble. Keys will be better prepared for this match, having beaten Kvitova, who is also a power player, in the third round. If Keys can keep up these numbers with her first serve she will definitely stand a chance against the elder Williams sister.
- Venus will be happy with the fact that Keys’ return of serve is not her strong point. Keys has won only 39% of the first serve returns (Venus 43%) and 57% of the second serve returns of her opponents (Venus 63%). Keys will have to return better to put pressure on Venus.
- Keys has been the better player when it comes to both converting and saving break points. Keys has won 45% of the break point opportunities she has created, compared to only 40% by Venus and has saved 63% of the break points she has faced, compared to 62% by Venus.
- Venus has been playing cleaner matches than Keys. She has a +1 winners-to-unforced errors differential on average per match, Keys on the other hand has a -3 differential.
- Keys has lost one set so far, while Venus has dropped a set in each of her last two matches.
- Venus Williams is yet to lose a match this year. She started by winning Auckland and now finds herself in the quarterfinals of a major for the first time since 2010. Keys, however, finds herself in the quarterfinals of a Grand Slam for the first time and she is bound to be nervous. Having Lindsay Davenport in her corner might lessen that nervousness to some extent.
It will all come down to two things:
- Keys’ nerves; and
- The after effects of two long three-setters on Venus Williams and the energy level she brings to the match. With Venus’ age and her Sjögren’s syndrome, she might be feeling the after effects in the quarterfinals.
Venus is the clear favorite in this match. However, I like Keys’ chances as well. Just like the previous match I am going to go with the underdog (Keys) making it to her first Australian Open semifinal.
Who are your picks?
NOTE: In the preview of the first two quarterfinals I went with the numbers, this time I am going against them. What fun is it analyzing the matches if you always have to go with the favorite. (photos: Jimmie48)