Del Potro needs 3rd-set tiebreak to win

Argentina's Juan Martin del Potro returns the ball to Britain's Andy Murray during their ATP World Tour Finals tennis match at the 02 Arena in London, Sunday, Nov. 22, 2009. (AP Photo/Sang Tan)

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Del Potro needs ... Argentina's Juan Martin del Potro returns the ball to Britain's Andy Murray during their ATP World Tour Finals tennis match at the 02 Arena in London, Sunday, Nov. 22, 2009. (AP Photo/Sang Tan)
Nadal loses to S... Robin Sonderling of Sweden reacts after defeating Rafal Nadal of Spain in their ATP World Tour Finals tennis match at the O2 Arena in London, Monday, Nov. 23, 2009 . Sonderling won the match 6-4, 6-4. (AP Photo/Alastair Grant)
ATP will not reo... Andre Agassi returns the ball to Pete Sampras during a friendly exhibition at the Venetian Hotel in Macau Sunday, Oct. 25, 2009. The two American tennis greats revisited one of the sport's greatest rivalries in the 1990s. They last played in the U.S. Open final in 2002. (AP Photo/Vincent Yu)
Wickmayer, Malis... Belgium's Yanina Wickmayer wipes a tear as she addresses the media at the King Baudouin stadium in Brussels, Thursday, Nov. 12, 2009. U.S. Open semifinalist Yanina Wickmayer was suspended for one year by a Belgian anti-doping tribunal on Thursday for failing to report her whereabouts to anti-doping officials three times. Wickmayer has denied any wrongdoing and said on her Web site she planned to appeal to the Court of Arbitration for Sport.(AP Photo/Yves Logghe)
Federer draws de... Roger Federer, left, of Switzerland, and Juan Martin del Potro, of Argentina, pose with their trophies following the men's finals championship at the U.S. Open tennis tournament in New York, Monday, Sept. 14, 2009. Del Potrol defeated Federer in five sets. (AP Photo/Charles Krupa)
Injured Roddick ... American Andy Roddick answers questions of journalists during a press conference of Shanghai ATP Masters 1000 tennis tournament at Qizhong Stadium Tuesday, Oct. 13, 2009 in Shanghai, China. Roddick retired in the first set of his second-round match of Shanghai Masters against Swiss Stanislas Wawrinka of Switzerland on Tuesday. (AP Photo/Eugene Hoshiko)
Djokovic wins Pa... Serbia's Novak Djokovic holds the trophy after defeating France's Gael Monfils during the final of the BNP Masters indoor tennis tournament in Paris, Sunday, Nov. 15, 2009. Third-seeded Novak Djokovic won the Paris Masters for the first time by defeating Frenchman Gael Monfils 6-2, 5-7, 7-6 (3) in Sunday's final. (AP Photo/Michel Euler)
Djokovic, Monfil... Novak Djokovic, of Serbia, reacts after beating Rafael Nadal, of Spain, 6-2, 6-3, during the semi-finals at the BNP Masters indoor tennis tournament in Paris, Saturday, Nov. 14, 2009. (AP Photo/Ian Langsdon, Pool)
Wickmayer critic... Belgium's Yanina Wickmayer addresses the media at the King Baudouin stadium in Brussels, Thursday, Nov. 12, 2009. U.S. Open semifinalist Yanina Wickmayer was suspended for one year by a Belgian anti-doping tribunal on Thursday for failing to report her whereabouts to anti-doping officials three times. Wickmayer has denied any wrongdoing and said on her Web site she planned to appeal to the Court of Arbitration for Sport.(AP Photo/Yves Logghe)
Federer loses to... Julien Benneteau, of France, reacts after beating Roger Federer, of Switzerland, 3-6, 7-6, 6-4, during BNP Masters indoor tennis tournament in Paris, Wednesday, Nov. 11, 2009. (AP Photo/Michel Euler)
Safin ends caree... Marat Safin of Russia, acknowledges applause during the BNP Masters indoor tennis tournament in Paris, Wednesday, Nov. 11, 2009. Safin ended his career with style with a 6-4, 5-7, 6-4 defeat by Juan Martin del Potro in the second round of the Paris Masters. The 29-year-old Safin, a two-time Grand Slam title winner, put on a great performance on center court Wednesday against the U.S. Open champion but was unable to extend his career for at least one more day. (AP Photo/Michel Euler)
Djokovic reaches... Novak Djokovic, of Serbia, returns the ball to Juan Monaco, of Argentina, during the BNP Masters indoor tennis tournament in Paris, Wednesday, Nov. 11, 2009.(AP Photo/Michel Euler)
No. 9 Zvonareva ... Vera Zvonareva of Russia reacts during her singles match to Caroline Wozniacki of Denmark at the WTA Tennis Championships, in Doha, Qatar Thursday, Oct. 29, 2009. (AP Photo/Kirsty Wigglesworth)
Serena sets WTA ... Sheikha Hind Bint Hamad Bin Khalifa Al-Thani, daughter of the Emir of Qatar, left, presents the trophy to Serena Williams of the United States after winning the singles final against Venus Williams of the United States at the WTA Tennis Championships, in Doha, Qatar Sunday, Nov. 1, 2009. (AP Photo/Kirsty Wigglesworth)
Serena tops Venu... Serena Williams, right, of the United States holds the trophy after winning the singles final against Venus Williams, left, of the United States at the WTA Tennis Championships, in Doha, Qatar Sunday, Nov. 1, 2009. (AP Photo/Kirsty Wigglesworth)
Safina retires w... Dinara Safina of Russia sits down injured as she retires from her singles match against Jelena Jankovic of Serbia at the WTA Tennis Championships, in Doha, Qatar Wednesday, Oct. 28, 2009. (AP Photo/Kirsty Wigglesworth)
Davydenko upsets... Nikolay Davydenko of Russia celebrates as he won the singles final against Rafael Nadal of Spain at Shanghai ATP Masters 1000 tennis tournament at Qizhong Stadium Sunday, Oct. 18, 2009 in Shanghai, China. Davydenko won the final, 7-6, 6-3. (AP Photo/Eugene Hoshiko)
Stosur wins Japa... Samantha Stosur of Australia serves to Caroline Wozniacki of Denmark during their semifinal match at the Japan Women's Open Tennis in Osaka, western Japan, Saturday, Oct. 17, 2009. Stosur won 6-0,4-6,6-4. (AP Photo/Itsuo Inouye)
Top-seeded Penne... Italy's topseeded Flavia Pennetta returns the ball to Romania's Ioana Raluca Olaro, during their quarterfinal match of the Generali Ladies tennis tournament in Linz, Austria, on Friday, Oct. 16, 2009. (AP Photo/rubra)
Nadal advances t... Rafael Nadal of Spain hits a ball against Ivan Ljubicic of Croatia at the quarterfinal match of Shanghai ATP Masters 1000 tennis tournament in Shanghai, China, Friday, Oct. 16, 2009. Nadal defeated Ljubicic 3-6, 6-3 after Ljubicic retiring from the match due to left hip injury on the third set. (AP Photo/Andy Wong)
Wozniacki reache... Caroline Wozniacki of Denmark returns to Aleksandra Wozniak of Canada during their quarterfinal match at the Japan Women's Open Tennis in Osaka,western Japan, Friday, Oct. 16, 2009. Wozniacki won 6-2, 7-6, 6-2. (AP Photo/Itsuo Inouye)
Cilic routs Nada... Croatia's Marin Cilic celebrates his win over Spain's Rafael Nadal in the semi-finals of the China Open tennis tournament in Beijing Saturday, Oct. 10, 2009. Cilic beat Nadal 6-1, 6-3. (AP Photo/Elizabeth Dalziel)
Del Potro upsets... Juan Martin del Potro, of Argentina, kisses the championship trophy after winning the men's finals championship over Roger Federer, of Switzerland, at the U.S. Open tennis tournament in New York, Monday, Sept. 14, 2009.(AP Photo/Charles Krupa)