Post-match statistical overview of Clijsters vs. Wozniacki quarterfinal

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Yesterday our loyal contributor Omair did a statistical analysis of the Australian Open quarterfinal between Kim Clijsters and Caroline Wozniacki, and the numbers spoke in Wozniacki’s favor. Despite that, gut feeling told Omair that the Dane was more likely to lose and that’s what happened. Now, let’s see Omair’s post-match review of the 6-3 7-6(4) match.

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)


  1. First serve of Wozniacki was key in her defeat. She was serving very well recently. A lot of aces. She said that she felt like Isner. Unfortunately, first ball was not good yesterday especially at the end of the second set. This could/should have saved her but didn’t. A third set would have been challenging for Kim against the most fitted women player.

  2. I watched the match and compared to the match against JJ she played a lot worse. She often hit right to Kim’s hitting zone leaving her with an easy job to finish off.
    I think she was really nervous out there because in the first set it was clearly shown that her plan A was not working and by the time she switched to plan B it was too late. Put up a good fight in the second set though.

  3. Come On !! Clijsters has to let go now, hot chicks like caroline are really getting annoyed by her habbit of stealing away the victories this important!!

  4. @ Marine, yes the numbers do say that! I guess the number one ranking was too much on her mind…

    @ Mohsin
    DO you watch tennis 😉 ?

  5. The stats show that it was a pretty clean performance from Kim, but Wozniacki didn’t bring her best tennis on the day with 1st serve points won and unforced errors her big downfall.


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