ISTANBUL — Serena Williams overcame physical problems as well as emotional distress to defeat Jelena Jankovic 6-4, 2-6, 6-4 Saturday and reach the WTA Championships final. The world No. 1 and defending champion, who will face China's Li Na in Sunday's final, put in a stumbling performance and twice sat weeping into her towel during change-overs. It was not clear what was bothering her, but she was in obvious discomfort. She walked slowly during changeovers and did not move well on the court. She also committed 40 unforced errors and hit 40 winners, and allowed a 5-1 final set lead to evaporate to within one point of 5-5 before finishing the match with three trademark heavy blows. “I'm relieved and just glad to be in the final,” said Williams. Li earlier beat Petra Kvitova 6-4, 6-2. Sunday's final will feature two players over the age of 30. “The oldest players have more experience on court,” said Li. “This year I was feeling more confident. I understand more what I should do on the court and off it.” Del Potro to face Federer in final Juan Martin del Potro of Argentina set up a Swiss Indoors title rematch against Roger Federer by beating Edouard Roger-Vasselin 6-4, 4-6, 6-2 in the semifinals Saturday. Federer tested his home fans' nerves before advancing to his eighth straight Basel final with a 6-3, 6-7 (3), 7-5 win against the 40th-ranked Canadian. The third-seeded Federer faltered when serving for the match at 5-3 in the second set, and fell 3-1 behind in the decider before rallying. The top-seeded del Potro came back strongly after a shaky spell when he let the second set slip away, and brushed aside the 65th-ranked Frenchman in the decider. “I made a lot of mistakes in the end of the second set,” the fifth-ranked del Potro said. “He was there taking chances. He has nothing to lose in this match.” Federer, who lost to del Potro in the 2012 final, played 40th-ranked Vasek Pospisil of Canada in the second semifinal. A five-time champion in his hometown event, Federer is seeking just his second title this season. He last played a final in June, when winning the grass-court event at Halle, Germany. “When you are close to playing Federer in the final it is like some extra pressure for me,” said del Potro, who has won three hard-court titles this season. “I would like to play him in the final because, for me, it is going to be more interesting.” Federer showed his lethal best when it mattered most as he beat Bulgarian Grigor Dimitrov 6-3, 7-6 (7/2) Friday to reach the semifinals. Federer, a five-time champion in the city of his birth, played a second-set tiebreaker to perfection against the 22-year-old. In the other quarterfinal, Pospisil beat Ivan Dodig 7-6 (13/11), 6-4. — Agencies
