Top-ranked Rafael Nadal rallied for another five-set victory Saturday, overcoming knee problems, an umpire's warning and a tough challenge from a hard-hitting German to reach the fourth round of Wimbledon.
Nadal battled back from two-sets-to-one down for the second straight match to defeat Philipp Petzschner 6-4, 4-6, 6-7 (5), 6-2, 6-3 in a Centre Court slugfest.
Defending women's champion Serena Williams had a much easier time, serving 19 aces in a straight-sets win against Dominika Cibulkova that set up a fourth-round matchup with former champion Maria Sharapova.
The top-seeded Williams had at least two aces in each of her nine service games and overpowered the 46th-ranked Slovak 6-0, 7-5.
The second-seeded Nadal, who won the title in 2008 but missed last year's tournament due to tendinitis in his knees, called for the trainer four separate times for treatment on his left arm and right knee but never looked badly hurt.
"I hope I'll be fine," Nadal said. "I don't know. I'm going to check. It's not a big problem. It's a long season for me. I have played a lot of matches the last few months."
Nadal said he will definitely play Monday's match against France's Paul-Henri Matthieu, who beat Thiemo de Bakker in four sets.
"I am here to try my best and to try to keep in the tournament," he said.
Fourth-seeded Andy Murray followed Nadal on Centre Court and beat Frenchman Gilles Simon 6-1, 6-4, 6-4, keeping alive Britain's hopes for a first homegrown male champion since 1936.
Murray now will face 18th-seeded American Sam Querrey, who overcame Belgian Xavier Malisse to reach the fourth round here for the first time.
Williams, meanwhile, won 37 of 43 service points and held at love five times. She won 19 of her first 20 service points, with Cibulkova putting only four returns in play in that stretch.
"Serving that well feels awesome," Williams said. "I serve well at Wimbledon for some unknown reason. I want to keep doing it."
The first set lasted just 18 minutes. It was the third match in a row that Williams won the first set 6-0.
Williams credited Cibulkova with raising her game but was unhappy with her own performance in the second set.
"I just kind of came off the gas a little too much," she said. "Just can't do that in big Grand Slams like this."