DPA/IANS

New York, Sep 9: Rafael Nadal rallied to defeat Gael Monfils 6-7(4), 6-3, 6-1, 6-3 while Andy Murray was humbled by Croat Marin Cilic 7-5, 6-2, 6-2 at the US Open tennis.

Nadal, playing his first Grand Slam since returning after two months' rest to his injured knees, had worries coming to the court Tuesday after suffering an abdominal strain, but other than a small taping visible when he changed shirts, the problem was unnoticeable over the two-and-three-quarter-hours win.

The victory has moved Nadal closer to top-ranked Roger Federer and ahead of Murray in the ATP rankings due out Monday.

Nadal improved to 5-1 over the flamboyant but inconsistent Frenchman Monfils and next plays Fernando Gonzalez.

The Chilean claimed his spot over Jo-Wilfried Tsonga 3-6, 6-3, 7-6(3), 6-4 to complete French misery Tuesday.

Nadal was pleased to reach his third New York quarter-final and said he never worries about rankings.

"I'm here to play my best and try to enjoy my comeback," the Spaniard said. "To make the quarter-finals is a big result for me. I'm improving every day. It's not easy to come back, but it is much better so far than what I expected."

Murray was stunned in the defeat inflicted in little more than two hours as his opponent Cilic fired 35 winners, including 10 aces, to advance into his career-first Grand Slam quarter-final.

The Scot said that while he's been bothered by his left wrist for a few days, it was not the reason for the one-sided loss.

"I've had a problem with it for a week or so, but, regardless, I just struggled today," he said. "I played poorly."

"I'm obviously very disappointed," Murray said. "After the way that the last three Slams went, I felt like I had actually played well and lost. Today, it didn't feel like I played well."

Cilic marked his turnaround from the 10th game of the opening set when he saved two Murray set points to instantly reverse the momentum.

"That was the turning point," Cilic said after defeating his first top-three-ranked player.

"It was a relief for me," Cilic said. "I got more into the match and played tactically very well. He was missing a lot today, and it was very windy and not easy to play in."

Cilic is to face off against Juan Del Potro after the sixth seed reached his third Grand Slam quarter this season with a defeat of 2003 finalist Juan Carlos Ferrero 6-3, 6-3, 6-3.

Former women's champion Kim Clijsters made it to the semifinals as she played her first Grand Slam since quitting the game earlier this decade, beating China's Li Na 6-2, 6-4.

The success for the 26-year-old Belgian, who retired two and a half years ago for marriage and motherhood, could send the one-time number one back to a ranking in the 50s a month after her comeback to the Women's Tennis Association (WTA).

"It's a nice feeling to have, knowing, you know, I was able to win it in two sets," Clijsters said. "Even in that second set, I got a little bit closer, but I was just able to finish it off in straights."

She next faces a test with world number two and defending champion Serena Williams, who beat Italian 10th seed Flavia Pennetta 6-3, 6-4.