NEW YORK — Rafael Nadal had sweated through three shirts by the start of the second set of a fourth-round U.S. Open match Thursday night.
Frenchman Gael Monfils was pummeling the Spaniard and had committed a chest-thumping, arm-raising, bellowing-to-the-heavens celebration after winning one set, in a tiebreaker.
But Nadal, even with a sore abdominal muscle and the rustiness he is still shedding from knee tendinitis, just kept hitting harder until Monfils was bent over searching for air. The third-seeded Nadal withstood the 13th-seeded Monfils' early barrage and won going away, 6-7 (3), 6-3, 6-1, 6-3, at Arthur Ashe Stadium.
Nadal's willingness to fight back after one bad set was in stark contrast to the way 2008 Open finalist Andy Murray performed. Murray, seeded second, made a lifeless exit, losing, 7-5, 6-2, 6-2, to 16th-seeded Marin Cilic of Croatia. Murray called the defeat "the worst of my career."
A different tempo was set in Ashe Stadium in the first night match, one that included sky-scraping lobs, line-kissing ground strokes, 115-mph serves and Serena Williams pumping her fists and shouting "Come on!" after her final, eye-popping forehand.
Williams, the defending champion and seeded second this year, conquered 10th-seeded Flavia Pennetta of Italy, 6-4, 6-3. Former No. 1 Kim Clijsters won her quarterfinal as well, 6-2, 6-4 over 18th-seeded Li Na of China. It was Clijsters' 12th straight Open win (she hasn't played here since she won her only major title in 2005), and it set up a glamour semifinal against Williams.
It had been Clijsters who eliminated Serena's sister, Venus, in the fourth round Friday. Though Clijsters is unseeded after a two-year retirement, Serena suggested that even though she has a career 7-1 record against the Belgian, the 26-year-old wife and mother of an 18-month-old daughter is playing better than ever.
"I just saw how well she moved," Serena said. "Seems like she's faster than what she was before. I was thinking maybe I should have a baby and come back."
Clijsters, who won her 100th Grand Slam tournament match, said, "I have a really good feeling the way I stayed focused after the Venus match. Like I didn't lose focus just by everything that was going on around me. . . . I think that's something that I learned from the past, when you beat big players not to get carried away and just refocus on a match like today."
Nadal is making his own mini-comeback. The 23-year-old Spaniard, who left No. 1-ranked Roger Federer in tears after the 2008 Wimbledon final and 2009 Australian Open final, had been eliminated early at the French Open, where he had won four straight titles. He couldn't defend his Wimbledon title because of knee tendinitis and he needed on-court treatment on his sore abdominal muscle here during his third-round win over Nicolas Almagro.
And when the excitable 23-year-old Monfils won the first set and performed his revved-up celebration, it seemed as if the ailing Nadal would have every excuse to save the pain and try again next year.
Instead Nadal raised the level of his grunting and power and by the end of the second set Monfils was bent over at the waist, gasping for air.
From there Nadal was in command.
"The knees are perfect," Nadal said. "That gives me a lot of confidence."
As for the stomach muscle, Nadal begged off. He said he will wait until after the tournament to speak about any new pain.
Monfils admitted he got tired. "That's a credit to Rafa," Monfils said. "He played more deep, more heavy, more flight on his shots. I think it was a bit tough for me to keep going like that."
Nadal has already won six major titles but has never won here. Up next for him is 11th-seeded Fernando Gonzalez of Chile, who beat seventh-seeded Jo-Wilfried Tsonga, 3-6, 6-3, 7-6 (3), 6-4.
And Nadal will think no further ahead than that match. "I play the quarterfinals against a very tough opponent," he said. "I'm not thinking more than that."
Cilic, who served two aces in the final game, has a good grasp of what this means.
"It was my fifth appearance in the final 16," Cilic said. "Now it's the first time I got through. Now I've made that extra step."
The next step is a battle against sixth-seeded Juan Martin del Potro, who had an easy 6-3, 6-3, 6-3 win over 24th-seeded Juan Carlos Ferrero on Tuesday.
And Murray was left offering reasons for his loss that were as dispiriting as his play during the match.
"I didn't find a way to get myself into the match," he said. "I just couldn't find my way into games."