NEW YORK: Six-time Grand Slam champion Rafael Nadal, trying to complete a career Slam, and British second seed Andy Murray withstood fightbacks to reach the third round at the US Open.

Spanish third seed Nadal weathered the storm to defeat Germany's Nicolas Kiefer 6-0, 3-6, 6-3, 6-4. The reigning Australian Open showed no sign of the knee trouble that kept him out two months and caused him to miss Wimbledon.

"I feel good," Nadal said. "I started playing well but I think he started low and later played better. It's difficult like that because you are not on rhythm. Nicolas is a very difficult player and I'm very glad to beat him."

Murray, last year's US Open runner-up, answered a sluggish second set by winning seven games in a row and fired 15 aces in defeating Chile's Paul Capdeville 6-2, 3-6, 6-0, 6-2.

"I played three very good sets and one poor one," Murray said. "You're allowed to play a bad set sometimes but I came back well from it. I just felt a litle lethargic, low in energy. I don't know why.

"But I managed to pick it up when I needed to."

The 22-year-old Scotsman, trying to become the first British man to win a Grand Slam title since Fred Perry in 1936, will play for a spot in the last 16 against 196th-ranked US wild card Taylor Dent.

All 16 top seeds advanced to the third round, the first time this has happened in any Grand Slam tournament in the 41-year Open era, as sixth seed Juan Martin del Potro, seventh seed Jo-Wilfried Tsonga, ninth seed Gilles Simon, 11th seed Fernando Gonzalez and 13th seed Gael Monfils also won second-round matches.

Nadal, whose best US Open showing was last year's semi-final run, will play for a spot in the fourth round against countryman Nicolas Almagro, who dispatched American Robby Ginepri 6-7 (7/9), 6-2, 6-3, 4-6, 6-4.

"He's a very good player with a big serve," Nadal said. "I'm just going to try to play my best tennis and have some chances to win."

Nadal breezed through the first set in 24 minutes but Kiefer broke him twice to claim the second set, his only set ever taken from Nadal in five meetings.

The match turned in the eighth game of the third set when the Spanish left-hander capitalized on his fourth break-point chance with a forehand winner to seize a 5-3 edge, then held at love to claim the set.

Nadal collected a final break in the seventh game of the last set when Kiefer sent a backhand beyond the baseline and served out for the triumph.

Murray squandered two break points in the opening game but Capdeville netted a backhand in the fifth game to surrender a break and Murray broke again in the seventh then held to claim the set.

Capdeville, trying to reach his first Grand Slam third round, broke Murray in the fourth game of the second set and served out to pull even, finishing on back-to-back aces.

Murray responded by winning the next seven games, sweeping the third set in 21 minutes to re-establish control, then breaking at love in the fourth game of the fourth set and breaking again in the last game.

"I was happy with how I responded. When you go behind in Slams you have to respond quickly," Murray said. "I played one bad service game to give him some confidence in the second set but I was happy with the way I came back."

Dent, playing in his first US Open since 2005 due to back injuries, outlasted Spain's Ivan Navarro 6-4, 5-7, 6-7 (1/7), 7-5, 7-6 (11/9) after four hours and 12 minutes to book his first meeting with Murray in four years.

"Murray is tough. It's going to be rough. There's no way around it," Dent said. "My execution is not where I want it to be but I'm going to go out there and fight as hard as I possibly can.

"Even if it's 6-0, 6-0, 6-0, I'm going to give him everything I've got."

Del Potro, who could play Murray in a quarter-final, fired 13 aces to beat Austrian Jurgen Melzer 7-6 (8/6), 6-3, 6-3. The French Open semi-finalist from Argentina will face Austrian Daniel Koellerer for a place in the last 16.

Spain's Juan Carlos Ferrero, the 2003 French Open champion and US Open runner-up, fired 17 aces to beat German Philipp Petzschner 1-6, 3-6, 6-4, 6-2, 6-4. Up next is Frenchman Simon, with Del Potro possibly awaiting the winner.

Tsonga beat Finland's Jarkko Nieminen 7-5, 6-3, 6-4. The 2008 Australian Open runner-up meets fellow Frenchman Julien Benneteau for a spot in the last 16, a level Tsonga has reached at every Slam but this one.

Chile's Gonzalez fired 26 aces in ousting Frenchman Josselin Ouanna 6-4, 6-7 (5/7), 6-3, 6-4 while France's Monfils blasted 17 aces in defeating Germany's Andreas Beck 6-3, 7-5, 6-3.