Defending champion Roger Federer extended his winning streak to 20 straight matches despite being stretched to three sets Thursday in a 6-3, 5-7, 6-4 victory over Andreas Seppi of Italy in the Qatar Open quarterfinals. The third-ranked Federer set up a rematch of last year's semifinals against Jo-Wilfried Tsonga. The sixth-ranked Frenchman defeated Albert Ramos of Spain 6-2, 6-1. Rafael Nadal also reached the semifinals, playing some of his best tennis this week in dispatching of Mikhail Youzhny 6-4, 6-4. In the final quarterfinal match, Gael Monfils of France beat Viktor Troicki of Serbia 6-2, 6-3.. The 30-year-old Federer, who is 26-3 at the Qatar Open and is looking to win his fourth title in Doha, hasn't lost since falling to Novak Djokovic in the US Open semifinals. “I thought I started well. I was able to play aggressive, not giving too much rhythm. He was obviously missing more shots due to that,” Federer said. “I thought he was a better player in that second set and deserved that set, and then the third set was close. I had my chances, he had his chances. But I was able to take mine. “I definitely think Seppi, he's a good return player,” Federer said. “When you give him too many second serves, he can take advantage of that.” Tipsarevic in quarters In Chennai, India, top seed Janko Tipsarevic of Serbia and No. 2 Nicolas Almagro of Spain eased into the quarterfinals of the $450,000 ATP Chennai Open Thursday. Tipsarevic outplayed Indian wildcard Yuki Bhambri 6-1, 6-3. The 10th-ranked Almagro had an even easier passage into the last eight after Steve Darcis of Belgium withdrew from the second round match with a shoulder injury. Goffin came from behind to knock out Andreas Beck of Germany 4-6, 6-4, 6-2. Yuichi Sugita of Japan defeated Yen-Hsun Lu of Taiwan 7-6 (7/5), 6-4 in two hours and 21 minutes.
