Roger Federer, Rafael Nadal and Serena Williams -- players with a combined 12 Wimbledon titles -- all won in straight sets Saturday to move into the fourth round and keep up their pursuit of even more championship trophies at the All England Club.

Six-time champion Federer beat David Nalbandian 6-4, 6-2, 6-4 to move closer to equaling Pete Sampras' record of seven Wimbledon titles.

Two-time winner and defending champion Rafael Nadal committed only three unforced errors in a 7-6 (6), 7-6 (5), 6-0 victory over Gilles Muller, a 92nd-ranked wild card from Luxembourg.

Williams, chasing a third straight title and fifth overall in her comeback from nearly a year out with serious health problems, served 10 aces in beating 26th-seeded Maria Kirilenko 6-3, 6-2.

In a match that had been suspended after the first set because of darkness Friday, Nadal never lost serve in defeating the 92nd-ranked wild card from Luxembourg 7-6 (6), 7-6 (5), 6-0 on Court 1.

Muller is the last player other than Roger Federer to beat Nadal at Wimbledon, in the second round in 2005.

Nadal will next face another Grand Slam champion, 2009 U.S. Open winner Juan Martin del Potro, who beat Gilles Simon 7-6 (8), 7-6 (5), 7-5. The Argentine missed most of 2010 after surgery on his right wrist.

"He's a fantastic player. He's one of the best players of the world," said Nadal, who for the first time advanced to Wimbledon's round of 16 without dropping a set. "He had an important injury last year, but he's here now all the time and he's at his top level.

"It will be a very difficult match. It will be a fantastic test and I have to be playing my best if I want to have chances, and that's what I'm going to try."

In women's play, 2004 champion Maria Sharapova and top-seeded Caroline Wozniacki won in straights set to reach the round of 16.

Nadal, who saved two break points in the first set Friday against Muller, made no unforced errors Saturday in the second set. But Muller managed to stay even until he sliced a backhand into the net after a long rally to give Nadal a 6-5 edge in the tiebreaker. The Spaniard closed the set in the next game with a forehand winner, then won six straight games, finishing with an ace.

"It was a very difficult match to play, especially the first two sets, when I had not one chance to break him," Nadal said. "It's like a lottery. I'm happy about how I played the tiebreaks, very solid with my serve. ... I feel like in the third set I started to play really, really good."

Nadal said he felt discomfort in his right leg, but that it was not related to the two heavy falls he took at the baseline during the match.

"I started to feel the leg a little bit more tired than usual," he said. "But I played today without problems, and now I (have) one day and a half to rest and recover. I hope it will be perfect for Monday."

Sharapova struggled with her game but reached the fourth round by beating Klara Zakopalova 6-2, 6-3. The fifth-seeded Russian, the only champion in the women's draw other than the Williams sisters, had 21 unforced errors and four double-faults in an inconsistent baseline performance in the wind on Court 2.

But, after falling behind 3-1 in the second set, Sharapova lifted her game to win five games in a row to finish off the 35th-ranked Czech player. Zakopalova had trouble with her footing, slipping at least four times along the baseline.

Sharapova pumped her fist and shouted "Come on!" after hitting a forehand service return winner to break for 5-3 in the second set, then finished the match in the next game with another forehand winner down the line.

Sharapova hasn't reached the semifinals since 2006. She will next face 20th-seeded Peng Shuai of China, who beat Melinda Czink of Hungary 6-2, 7-6 (5).

Wozniacki, still looking for her first Grand Slam title, swept Jarmila Gajdosova 6-3, 6-2 to make the fourth round for the third straight year. Wimbledon is the only major championship in which the Dane has not reached at least the quarterfinals.

Also advancing to the final 16 among the men was last year's runner-up, Tomas Berdych. The sixth-seeded Czech needed only seven points to complete a 6-2, 6-4, 6-3 win over Alex Bogomolov Jr. of the U.S. The match had been suspended because of rain with Berdych leading 4-3, 15-0 in the third set Friday.

Berdych will next play 10th-seeded Mardy Fish, the last American man left in the tournament. He advanced when Robin Haase retired at 1-1 in the fourth set because of injuries. Fish was up two sets to one, 6-3, 6-7 (5), 6-2.

Ninth-seeded Gael Monfils lost to 93rd-ranked Polish qualifier Lukasz Kubot 6-3, 3-6, 6-3, 6-3. Kubot, who won three qualifying matches to get into the main draw, also reached the round of 16 at the 2010 Australian Open.

No. 18 Ana Ivanovic, a former top-ranked player and 2008 French Open champion, was knocked out by Petra Cetkovska, 6-2, 7-6 (0). No. 9 Marion Bartoli beat Flavia Pennetta 5-7, 6-4, 9-7.