<p>Li Na defeated Jelena Jankovic at the WTA Championships on Thursday, meaning the battle for the two semifinal spots in the White Group will go on.<br /><br /></p>.<p>Li had routed Jankovic in the fourth round of the US Open, but this time it was a much different story as the two battled two hours and 11 minutes before the No 4-seeded Chinese emerged with a 6-3, 2-6, 6-3 win over the No 7 seed Serbian.<br /><br />It was an extremely streaky match -- never did either player win fewer than two games in a row at any point -- but Li held her nerve well towards the end, winning three straight games from 3-all in the third set to emerge victorious in the lone game of the season-ender on Thursday.<br /><br />Li is now 2-0 in the White Group, while Jankovic and Victoria Azarenka are 1-1, and Sara Errani 0-2.<br /><br />World No 1 Serena Williams beat Agnieszka Radwanska for the eighth time in eight matches to move ominously towards the semifinals on Wednesday.<br /><br />The American was again too strong for the Pole in a 6-2, 6-4 victory to stay in charge of Red Group with one more round-robin match to come against Petra Kvitova, another player to whom she has never suffered defeat.<br /><br />“Radwanska definitely played pretty well. Am I happy? I guess. I'm happy to still be alive in the tournament. But, you know, I can always look to improve on some things,” Williams told reporters after her 75th match win of a dominant year.<br /><br />Radwanska, whose only set against the 32-year-old Williams came in the 2012 Wimbledon final, is unlikely to survive the group after two defeats so far.<br /><br />Del Potro shines<br /><br />Top seed Juan Martin del Potro defeated Marcos Baghdatis for the second time in a month on Thursday to advance to the Swiss Indoors quarterfinals on Thursday at Basel.<br /><br />Defending champion Del Potro followed up on his Japan Open victory over Baghdatis, the 2005 finalist, with a 6-1, 6-2 win in 73 minutes. The Argentine bext faces qualifier Paul-Henri Mathieu, who defeated Michael Llodra 6-4, 6-3. <br /><br />Vasek Pospisil reached his third ATP quarterfinal as he defeated Tomas Berdych’s conqueror, Ivo Karlovic, 6-3, 6-3. France’s Edouard Roger-Vasselin built on his first-round upset win over Stanislas Wawrinka by reaching the quarterfinals with a 7-5, 6-3 win over Tobias Kamke. <br /><br />Roger-Vasselin meets Daniel Brands in the last eight after the German defeated Lukasz Kubot 6-2, 6-4.</p>
<p>Li Na defeated Jelena Jankovic at the WTA Championships on Thursday, meaning the battle for the two semifinal spots in the White Group will go on.<br /><br /></p>.<p>Li had routed Jankovic in the fourth round of the US Open, but this time it was a much different story as the two battled two hours and 11 minutes before the No 4-seeded Chinese emerged with a 6-3, 2-6, 6-3 win over the No 7 seed Serbian.<br /><br />It was an extremely streaky match -- never did either player win fewer than two games in a row at any point -- but Li held her nerve well towards the end, winning three straight games from 3-all in the third set to emerge victorious in the lone game of the season-ender on Thursday.<br /><br />Li is now 2-0 in the White Group, while Jankovic and Victoria Azarenka are 1-1, and Sara Errani 0-2.<br /><br />World No 1 Serena Williams beat Agnieszka Radwanska for the eighth time in eight matches to move ominously towards the semifinals on Wednesday.<br /><br />The American was again too strong for the Pole in a 6-2, 6-4 victory to stay in charge of Red Group with one more round-robin match to come against Petra Kvitova, another player to whom she has never suffered defeat.<br /><br />“Radwanska definitely played pretty well. Am I happy? I guess. I'm happy to still be alive in the tournament. But, you know, I can always look to improve on some things,” Williams told reporters after her 75th match win of a dominant year.<br /><br />Radwanska, whose only set against the 32-year-old Williams came in the 2012 Wimbledon final, is unlikely to survive the group after two defeats so far.<br /><br />Del Potro shines<br /><br />Top seed Juan Martin del Potro defeated Marcos Baghdatis for the second time in a month on Thursday to advance to the Swiss Indoors quarterfinals on Thursday at Basel.<br /><br />Defending champion Del Potro followed up on his Japan Open victory over Baghdatis, the 2005 finalist, with a 6-1, 6-2 win in 73 minutes. The Argentine bext faces qualifier Paul-Henri Mathieu, who defeated Michael Llodra 6-4, 6-3. <br /><br />Vasek Pospisil reached his third ATP quarterfinal as he defeated Tomas Berdych’s conqueror, Ivo Karlovic, 6-3, 6-3. France’s Edouard Roger-Vasselin built on his first-round upset win over Stanislas Wawrinka by reaching the quarterfinals with a 7-5, 6-3 win over Tobias Kamke. <br /><br />Roger-Vasselin meets Daniel Brands in the last eight after the German defeated Lukasz Kubot 6-2, 6-4.</p>