New York, Sep 5 - Rafael Nadal and Andy Murray advanced into the fourth round of the men's singles event at the US Open tennis here Sunday, while Samantha Stosur set up a quarterfinal clash against Vera Zvonareva in the women's singles.

Nadal won 7-6 (5), 6-1, 7-5 in 2 hours 39 minutes against David Nalbandian of Argentina.

The Spaniard will play Gilles Muller of Luxembourg for a place in the quarterfinals at the final Grand Slam of the year. Muller breezed past Russia's Igor Kunitsyn 6-1, 6-4, 6-4.

British No. 1 Murray romped past 25th seed Feliciano Lopez 6-1, 6-4, 6-2, easily moving to the fourth round.

The win took the Scot, who is in pursuit of his first Grand Slam title, an hour and 54 minutes and secured the fourth seed a rematch with the American prospect, Donald Young, who embarrassed him in their only meeting at Indian Wells in March.

Andy Roddick, the 21st seed from the United States and the champion in 2003, won 6-1, 6-4, 7-6 (5) against Frenchman Julien Benneteau and will face David Ferrer, the fifth seed from Spain for a quarterfinal place.

Ferrer moved on, also in straight sets, against 26th seed Florian Mayer from Germany 6-1, 6-2, 7-6 (2).

About two hours later after the defending champion's victory, the 25-year-old Nadal suddenly slumped to the floor under a large table because of right leg cramps during a press conference.

"I just have cramping in my leg, that is all," Nadal said in a statement after the interview room was locked for about 10 minutes while trainers and his family attended to him. "That is why I fell. It was so painful."

In women's draw, Australian Stosur lost the longest tiebreaker 15-17 in women's Grand Slam, but managed to reach the quarterfinals for the second consecutive year by outlasting Russian 25th seed Maria Kirilenko 6-2, 6-7(15), 6-3 in 2 hours and 37 minutes.

Stosur will next challenge Russia's top player Zvonareva, who dismantled 22nd seed German Sabine Lisicki 6-2, 6-3.

The second set alone lasted 84 minutes and was decided by the longest ever tiebreak in women's tennis at a Grand Slam level.

Ninth-seed Stosur had five match points in the epic second set tie-breaker, but was dragged into the deciding set, where the Australian won the contest on her eighth match point when Kirilenko hit her backhand wide.

The 26th seed Italian Flavia Pennetta overpowered China's Peng Shuai 6-4, 7-6 (6) to book her place in the last eight.

The Italian veteran will face unseeded German Angelique Kerber, who defeated Romanian Monica Niculescu 6-4, 6-3.

In other men's contest, Juan Martin Del Potro of Argentina, the 2009 US Open champion and the 18th seed this year, lost 4-6, 7-6 (5), 6-2, 7-6 (3) to Gilles Simon, the 12th seed from France, in a 3 hour and 57 minute match.

Donald Young became one of the four American men players rolling on as the 22-year-old got into the tournament as a wild-card entrant, winning 7-5, 6-4, 6-3 against Juan Ignacio Chela, the 24th seed from Argentina.

John Isner was also one of the American bundle in the last 16 as the 2.06-metre giant served 17 aces in beating his countryman Alex Bogomolov 7-6, 6-4, 6-4.  (IANS)