WIMBLEDON, England -- Defending champion Rafael Nadal beat Gilles Muller in straight sets Saturday to reach the fourth round at Wimbledon, committing only three unforced errors in a masterful display that keeps the Spaniard on course for a third title at the All England Club.
In a match that had been suspended after the first set because of darkness Friday, Nadal hit 36 winners and never lost serve to defeat 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 next will 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," Nadal said. "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."
Federer advanced to the fourth round by beating 2002 runner-up David Nalbandian 6-4, 6-2, 6-4.
Federer was broken once in the first set but dominated the rest of the way on Centre Court against Nalbandian, the 2002 Wimbledon runner-up from Argentina. Nalbandian received treatment on his right thigh several times but showed no visible sign of injury.
It was the 19th career meeting between the two, with Federer now leading 11-8.
"A guy who can beat me eight times knows how to do it nine times, and that's why I'm really pleased to come through," said Federer, whose only wobble came when he blew an easy smash on his first match point.
Federer, who lost to Tomas Berdych in the quarterfinals in 2010, said he is playing better than last year. He hasn't dropped a set so far.
"Maybe I'm just a bit more confident on my serve," he said. "And then obviously more relaxed on the baseline and on the return, and it seems like it's working. But it's only the first week, and I hope I can keep it going."
Nadal, who saved two break points in the first set Friday against Muller, was credited with zero 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."
Also advancing to the final 16 among the men was last year's runner-up, 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 next will 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.
Fish saved all three break points he faced and won 41 of 53 points
he played at the net. He accumulated 20 break points on Haase's
serve, converting three.
Two-time French Open runner-up Robin Soderling lost to 18-year-old Bernard Tomic 6-1, 6-4, 7-5. Tomic, a 158th-ranked Australian, is playing at Wimbledon for the second time. He lost in the first round last year.
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, is the first Pole to reach the fourth round at Wimbledon since Wojtek Fibak did it in 1981.
Information from The Associated Press was used in this report.