Rafael Nadal overcame a gritty performance by 32-year-old Nicolas Kiefer of Germany to score a 6-0, 3-6, 6-3, 6-4 victory and advance to the third round of the US Open in New York, on Friday.

Nadal looked on his way to an easy victory, using his huge groundstrokes to whitewash the 129th-ranked Kiefer in just 24 minutes in the opening set.

Kiefer, cheered on by the Arthur Ashe Stadium crowd, came back to win the second set and gave the third-seeded Spaniard a tough test the rest of the way.

Nadal registered single service breaks in the last two sets to subdue Kiefer in three hours and advance to a third-round match against fellow Spaniard and 32nd seed Nicolas Almagro.

Kim Clijsters continued her stunning comeback to grand slam tennis when she outclassed school friend and fellow Belgian Kirsten Flipkens 6-0 6-2 on Friday to reach the fourth round.

The Belgian, back after two years off the tour, during which time she gave birth to her first child, needed just 62 minutes to book her place in the last 16.

The first set lasted just 27 minutes as 2005 champion Clijsters forced world number 93 Flipkens into a series of errors.

Flipkens led by a break at 2-1 in the second set but Clijsters ran through five successive games to set up a clash with third seed Venus Williams.

"I'm so glad that being back I was able to experience a match like today. Playing someone like Kirsten, it's really special for both of us," said the 26-year-old

Like the rush hour traffic trying to leave Manhattan for the long Labour Day weekend, Andy Murray got caught in a jam Friday before he steered his way out of trouble and into the third round.

Facing an opponent who had won just one match in his last nine tour-level events, world number two Murray had been expected to rout Chile's Paul Capdeville in straight sets.

Instead the Briton earned the dubious distinction of becoming the first man among the top 10 seeds to lose a set at Flushing Meadows this year before running out a 6-2, 3-6, 6-0, 6-2 victory.

"I played three very good sets and one poor one. But you're allowed to play a bad set sometimes," the 2008 runner-up said.

Serena Williams moved closer to her third grand slam title of the year by knocking out Spain's Maria Jose Martinez Sanchez in straight sets to reach the fourth round.

"She was serving really well, and I think especially in the second set," Williams said after the 6-3, 7-5 victory on a warm and near-cloudless day at Arthur Ashe Stadium.

"I just kept fighting, and every time I had a break point I felt like I had a chance to win one of them. I thought she served well. I couldn't get down about it."

Taylor Dent, playing his first US Open in four years after two back surgeries, won a five-set thriller over Ivan Navarro of Spain and high-fives from the crowd at the National Tennis Center.

The 28-year-old Dent, son of former Australian player Phil Dent and US player, the former Betty-Ann Grubb, cashed in his fourth match point to win a fifth-set tiebreaker 11-9 for a 6-4, 5-7, 6-7, 7-5, 7-6 win that put him into the third round.

The unlikely victory over the 27-year-old, 119th-ranked Navarro, lifted Dent to a third-round meeting with second seed Andy Murray of Britain.

"The crowd just never stopped," Dent told reporters. "They never stopped kind of being my third leg out on the court. They were just with me the whole time. When I started to turn it around, I mean, the emotions just boil over here."

Sania Mirza and Francesca Schiavone of Italy crashed out of the women's doubles after losing against the unseeded duo of Gisela Dulko of Argentina and Shahar Peer of Israel in the second round.

Sania and Schiavone made a smart recovery after losing the opening set but failed to deliver at crucial points in the decider to go down 2-6, 6-1, 5-7.

The opening set saw Dulko and Peer having the upper hand in service by firing three aces while Sania and Schiavone struggled with their serves as they dropped two of them to give away the first set 2-6 in 27 minutes.

The Indo-Italian pair staged a fine recovery in the second set as they tightened their service game and engaged their rivals in long rallies which they won most of the time.

Sania and Schiavone broke Dulko and Peer twice in the second set while giving them no chance to do the same.

Both the pairs reserved their best for the decider which lasted 68 minutes. Sania and Schiavone smashed three aces but they still failed to win the crucial points.

With most of the games being stretched to deuces, breaks points changed sides and Dulko and Peer converted more of them than their Indo-American opponents. Dulko and Peer converted two of the nine break points, while Sania and Schiavone won one of the seven that came their way.

Sania, who could not advance beyond second round in singles, is still in the fray in mixed doubles. She and Canadian Daniel Nestor will take on American duo of Carly Gullickson and Travis Parrott in the second round.