Previewing Friday's 'Elimination Matches' at the WTA Championships

Three days of the 2012 WTA Championships are in the books, with only one day left in round-robin play before the semifinals and finals this weekend.

Half of the semifinalist field is already set. Serena Williams is the winner of the Red Group, having gone 3-0 in round-robin play, and she will face the runner-up of the White Group. Maria Sharapova is the winner of the White Group, as she is 2-0 in round-robin play, and even if she loses tomorrow to Samantha Stosur, she would hold tiebreakers over Agnieszka Radwanska and Sara Errani, having beaten both earlier this week.

So, what's on tap for Friday? The two matches that will determine who will join Williams and Sharapova in the semifinals. In the Red Group, world No. 1 Victoria Azarenka will face Li Na, and in the White Group, Radwanska and Errani will square off.

Here's a look at the two "elimination matches," as the winner will move on to the semifinals while the loser will begin the two-month offseason.

No. 1 Victoria Azarenka vs. No. 8 Li Na

Since her clay season ended with middling results, Victoria Azarenka has been on an absolute tear and is playing the best tennis of any woman in the world besides Serena Williams.

In fact, Williams has been the only player Azarenka has not been able to solve since the French Open, as all four of Azarenka's losses in that time frame have come to her. That number excludes retirements, as in Montreal where she retired from her match against Tamira Paszek.

Azarenka's post-French Open resume reads like this: Beijing and Linz champion, Olympic bronze medalist, Wimbledon semifinalist and the US Open runner-up, as she served for the championship against Williams up 5-4 in the third set but was broken and was broken again to lose the set 5-7. Entering the WTA Championships, she had won 29 of her last 33 matches.

Azarenka's opponent in this match, Li Na, also entered the WTA Championships playing her best tennis of the season. She fared well on the North American hard courts, making the final in Montreal and winning the title in Cincinnati. At the US Open, however, Li fell in the third round to ascending British teenager Laura Robson. She also made the semifinals in Beijing.

Azarenka was a runaway freight train coming into the WTA Championships, riding an 11-match winning streak, but she's had to work hard in Istanbul, needing over three hours to dispatch Angelique Kerber 6-7 (11) 7-6 (2) 6-4 and losing to Williams 4-6 4-6.

Meanwhile, Li Na made Williams work hard for her win, pushing the first set to a tiebreaker but eventually losing the match 6-7 (2) 3-6. She then defeated an exhausted Kerber, who was playing her third match in as many days, 6-4 6-3.

The winner of this match will face Maria Sharapova on Saturday in the semifinals. Given their recent history, Sharapova is rooting hard for Li to win, as she holds an 8-4 record against her but is just 4-7 against Azarenka, including losses in four out of their five meetings this season.

There's also more to this match than meets the eye. With a win, Azarenka will secure the year-end No. 1 ranking, which will give her a big boost heading into 2013.

As for their head-to-head matchup, Azarenka and Li have played eight matches and split them, with Li winning four of their first five matches before Azarenka responded by winning the next three, including a round-robin win at last year's WTA Championships and wins in the Sydney final and Madrid quarterfinals.

Given the level of Azarenka's recent play, the motivation she has to win this match to lock up the year-end top ranking and her recent success against Li, I like Azarenka to win this match to set up yet another battle with Sharapova. But it won't be easy: I think that Azarenka will lose a set but prevail in three.

No. 3 Agnieszka Radwanska vs. No. 7 Sara Errani

If Serena Williams' historic summer is the best tennis story to come out of 2012, then Sara Errani's improbable resurgence into the top 10 has to be right behind it.

Errani started 2012 ranked No. 45 in the world and actually briefly slipped to No. 48, which was her ranking entering the Australian Open. She took advantage of an opened-up draw to make her first Grand Slam quarterfinal, where she gave world No. 2 and reigning Wimbledon champion Petra Kvitova everything she could handle before falling 4-6 4-6.

Now up to No. 34 in the world, Errani played fitfully in the next four months, winning three clay titles (Acapulco, Barcelona and Budapest) but losing her first matches in both Indian Wells and Miami, the two biggest nonmajor tournaments in the tennis season.

But her clay success was an omen of things to come, as Errani entered the French Open seeded 21st. After getting through the first two rounds, she entered a gauntlet of three Grand Slam champions and a former world No. 1.

Errani started by defeating 2008 French Open champion and former world No. 1 Ana Ivanovic in three sets before sweeping 2009 champion Svetlana Kuznetsova. In the quarterfinals, she swept a resurgent Angelique Kerber before outlasting 2011 US Open champion and 2010 French Open finalist Samantha Stosur in three sets. Unfortunately, Errani's magic ran out in the finals, as she would lose to Maria Sharapova 3-6 2-6, as Sharapova completed the career Grand Slam and regained the world's top ranking in the process.

Errani's stunning run to the final brought her to No. 10 in the world, but her form dipped slightly as she was knocked out of Wimbledon in the third round by a hot Yaroslava Shvedova and was on the receiving end of a Golden Set in the process (when one player wins all 24 points in a set).

At the US Open, Errani overcame a tricky first-round matchup against Garbine Muguruza, advancing all the way to her third semifinal of the season before falling to eventual champion Serena Williams 1-6 2-6. Her run in Flushing Meadows brought her ranking up to No. 7, 41 spots higher than it was eight months prior.

Meanwhile, Radwanska has enjoyed quite a bit of success herself in 2012, although her brief rise to No. 2 in the world didn't start from outside of the top 45.

At the Australian Open, Radwanska advanced to the quarterfinals before losing to eventual champion Victoria Azarenka. She went on to record an impressive result in Miami, defeating Maria Sharapova for the title.

At the French Open, Radwanska lost to Kuznetsova in the third round, but enjoyed a huge breakthrough in Wimbledon, making the final and taking the second set from Williams before bowing out, 1-6 7-5 2-6.

At the Olympics, Radwanska lost in the first round to Julia Goerges, and on the North American hard courts, her form dipped, as she lost twice to Li Na in the quarterfinals of both Montreal and Cincinnati. At the US Open, she battled her way to the fourth round before losing to Roberta Vinci.

When Radwanska and Errani take the court tomorrow, it will be a study in similar styles. Both players play with great touch and precision—you'll never see these two confused for being heavy hitters in the mold of Williams.

At the Championships so far, Radwanska defeated a virus-weakened Petra Kvitova, 6-3 6-2 and extended Sharapova to three sets and over three hours before losing 7-5 5-7 5-7. Errani began her tournament by losing to Sharapova 3-6 2-6 and defeating Stosur, who replaced Kvitova, 6-3 2-6 6-0.

On a head-to-head level, the two have played six times, with Radwanska winning five of the six meetings, including their last four encounters. The two have played once this season, with Radwanska sweeping Errani in Madrid, 6-0 6-1. Dig a little closer, and you'll see that Radwanska has won 10 out of the 12 sets the two have played, with Errani's only win coming in the Budapest qualifiers six years ago.

Radwanska has looked more impressive so far this week, even though she defeated an admittedly weakened Kvitova, she gave Sharapova everything she could handle. Meanwhile, Errani couldn't dent Sharapova and needed three sets to get past Stosur.

For these reasons, I see Radwanska triumphing over Errani and booking a spot in the semifinals against Serena Williams. And, unlike Azarenka, she won't need three sets to take care of business. No, Radwanska will win in straights.