Rafael Nadal advanced to the second round of the US Open Wednesday but a knee injury could hamper his chances of dethroning top-ranked Roger Federer.
The Spaniard battled through the pain and an inspired performance by Australian Alun Jones before winning 7-5, 3-6, 6-4, 6-1 in a two-hour, 45-minute affair in Arthur Ashe Stadium.
Second seeded Nadal hurt his left knee during practice three days ago and had the trainer wrap the joint after his service was broken by Jones in the third set for a 4-3 deficit.
"Maybe if I am in another tournament I would never have gone on the court today," he told reporters.
"But the US Open is a very big tournament for me.
"Two days ago I was much worse. Today I didn't move much but I played, so that's the good news."
The 123rd-ranked Jones had 60 unforced errors in the match because he refused to take the safe route against the three-times French Open champion.
Federer eased forward in his bid for a fourth straight title by defeating Chile's Paul Capdeville 6-1 6-4 6-4, setting up a third-round showdown with hard-serving American John Isner.
"I'm very happy the way I played," said Federer, who had 45 winners and only 11 unforced errors.
"I think I hit the ball well."
On the women's side, Belgian top seed Justine Henin needed just over an hour to defeat Bulgarian qualifier Tsvetana Pironkova 6-4, 6-0 on a cool, sunny day at the National Tennis Center.
"I just go step by step and try to build my confidence day after day," the 2003 champion said.
"In a grand slam, you have to be strong, win seven matches. It's tough. It's long."
Former champions Venus and Serena Williams both started slowly before hitting their stride and winning their second-round matches in straight sets.
Venus eased past Romanian Ioana Raluca Olaru 6-4, 6-2 while Serena defeated Italian Maria Elena Camerin 7-5, 6-2.
"I felt like I had opportunities and I didn't take them," Serena said.
"It should have been a different scoreline but that was only because I missed the wrong shots at the wrong time."
Third seeded Jelena Jankovic and number five Ana Ivanovic also advanced, moving closer to an all-Serbian match-up in the quarter-finals.
The major casualty of the day occurred on the men's side when seventh seed Fernando Gonzalez of Chile was ousted by Russian Teimuraz Gabashvili, 6-4, 6-1, 3-6, 5-7, 6-4.
Gonzalez, who made a rousing run to the Australian Open finals before losing to Federer, has lost his first match in the four summer hard court events he has played since reaching the third round at Wimbledon.
"This year I have had many disappointments," Gonzalez said.
"But this is tennis."
