The cramps started in his calves late in the second set, moved up to his hamstrings by the third and were gripping his thighs entering the fourth.

Sam Querrey knew if he didn't close out the match in a hurry, he would likely be out of the running in the U.S. Open.

The Thousand Oaks High graduate summoned enough energy for one last mad scramble and held on to defeat France's Nicolas Devilder 7-6 (6), 6-4, 4-6, 6-3 in the second round of men's singles on Thursday night in Flushing Meadows, N.Y.

"If I hadn't held serve in that last game, I would have been done," Querrey said. "I would have tried to keep going, but I would have really struggled."

The victory marked the first time the 20-year-old Querrey has reached the third round at the U.S. Open, and equals his best Grand Slam showing.

He's advanced to the third round of the Australian Open the last two years.

Facing a "talented little guy" in the 5-foot-8 left-handed Devilder, Querrey was forced to extend himself early by saving a set point in the first and winning it in a tiebreaker.

"It was a grind," the 6-foot-6 Querrey said. "A lot of those points were 20-ball rallies, and with my body type, I don't need to be doing that."

Querrey, who finished with 17 aces and 48 unforced errors, said the atmosphere on the grandstand court helped pull him through his discomfort. He rewarded the fans with a stirring rally on the third to last point of the 3-hour, 10-minute match.

"I went around the net with a drop shot at break point," said Querrey, ranked No. 55 in the world. "It was crazy, but I finally got it done. I threw my racket and put up both hands and the crowd gave me a standing ovation. It was an incredible match."

Querrey moves to the opposite end of the opponent spectrum with a showdown of giants in the third round.

He plays 6-foot-10 Ivo Karlovic, the No. 14 seed. Querrey has a 2-1 record against the fellow hard-serving Croatian.

"I am excited about that match," said Querrey as he prepared to get a massage for his cramping legs. "He is a good guy to play because I won't be moving side to side all the time."

Second-seeded Bob and Mike Bryan of Camarillo cruised to a 6-3, 6-2 victory over Nicolas Almagro and Pablo Andujar of Spain in the opening round of men's doubles.

"We haven't played a match in 10 days and it's nice to get one under the belt that wasn't super tough," Bob said. "We are getting into the tournament now, so we feel good, we feel focused and we feel ready."

The Bryans play Dominik Hrbaty and David Skoch in the second round.

But they won't be playing any mixed doubles. Mike's partner Lindsay Davenport pulled out on Thursday to keep her knee healthy for women's singles and doubles and Bob is resting his shoulder.