Angelique Kerber came to her first match at the WTA Championships and her first match as a Top 5 player as the only player at the tournament who has defeated Serena Williams this year and the sole loss in Serena's 27 previous matches was at the hands of Kerber. But in today's Red Group match, Serena earned a good old revenge, winning nine of 11 games from 3-all in the first set for a 6-4 6-1 victory. Serena's threatening first serve was at weak 44% and she hit just three aces, but at the net she won 17 of 20 points.

Serena's 2012 results have been mind-blowing. She's won 44 of her last 46 matches and her last 15 against Top 5 players. Not to mention her this year's titles: Charleston, Madrid, Wimbledon, Stanford, Olympics and US Open – all Premier-level or higher. She's practically unstoppable and the fact that she hadn't played since the US Open does not put her even slightly on the unprepared side.

Serena opens tomorrow's action in Istanbul, against Li Na. Kerber has a day off. (photo: © Neal Trousdale)

In the first match of the WTA Championships, in the White Group, Agnieszka Radwanska made her first career victory over Petra Kvitova at the very tournament where the Czech is defending her title. The Pole took advantage of Kvitova's numerous unforced errors and nervousness to record a routine 6-3 6-2 win.

First seven points of the match were Radwanska's (1-0 40-0) and even though Kvitova fought for a long time to hold her serve, eventually she was broken. In the next service game of Kvitova, Radwanska again earned triple break point, leading 3-0 40-0, but this time Kvitova came back and leveled the set. However, Radwanska regained control of the match and nothing could save Kvitova from her -18 differential of winners to unforced errors, compared to Radwanska's +6.

Kvitova has now spoiled two perfect records, 5-0 at the WTA Championships and 3-0 against Radwanska. Of course, nothing is lost yet when it comes to the WTA Championships, the round robin format gives you more than once chance. Kvitova has a day off tomorrow, while Radwanska will play the third match of the day against Maria Sharapova. (photo: © Neal Trousdale)

On Sunday night, the official draw ceremony took place at the $4.9-million WTA Championships in Istanbul, dividing the eight players into two round-robin groups. Serena Williams is the only multiple champion at the year-end finale and is 35-5 against the rest of the field combined (9-1 this season), while Sara Errani is 4-23 and is the only one with a negative head-to-head record against all the three players in her group. Let's have a closer look at the draw.

RED GROUP: (1) Victoria Azarenka, (3) Serena Williams, (5) Angelique Kerber, (8) Li Na

World No.1 Victoria Azarenka is a leader in match wins this season with 67, she's also a title leader with six (tied with Serena Williams), and this fall she's been 13-0 in matches and 26-0 in sets. Serena is fifth in the list of match wins this season with 53, even though inactive this fall, and has a stunning 10-1 head-to-head record against Azarenka. Moreover, two Grand Slams and the Olympics are among Serena's six 2012 titles and three of the six she won without losing a set.  Read more »

Our stats analyst Omair is already famous for his statistical articles and now he's inspired Ludolf, another reader of Women's Tennis Blog and fan of tennis numbers, to contribute his take on the WTA rankings, i.e. he compared the actual rankings with the performance of players at the biggest events – Grand Slams and WTA Championships. Enjoy!

The WTA ranking does not rank properly the strength of players in the sense of the ability to win a match or a tournament. The main reason is that it is cumulative and therefore underestimates players without a sufficient number of tournaments. We need to compute an average to avoid this. Moreover, the WTA ranking considers tournaments with weights not depending on the quality of players on them.

To achive the above-mentioned goal it seems to be more appropriate to take the average result from majors and the WTA Championships, the tournaments where the best players are almost always present. By the result of a player we mean the number of her losses (including the rounds which she did not achieve), i.e. 0 for the winner, 1 for the defeated finalist, 2 for defeated semifinalists, and so on. The results for the last 52 weeks are presented in the table, completed by the WTA ranking (after the Australian Open) for comparison. (FO: French Open, W: Wimbledon, USO: US Open, WTA: WTA Championships, AO: Australian Open)

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Petra Kvitova is the hottest player of the moment with her WTA Championships title and the year can also be considered hers, as she won Wimbledon as one of her six titles in 2011. The Czech is now enjoying her career-high ranking of number two and the next season is expected to be more than bright for this 21-year-old. Now let's see how little Kvitova was handling the tennis racquet 17 years ago.

Petr, thank you for telling me about the video! Read more »