NEW YORK — As a kid, Andy Roddick was hard-pressed to come up with a better birthday treat than going to the US Open with his mom. At nine, he was thrilled to be on the scene while Jimmy Connors made a stirring run to the semi-finals.

"I'd get here for the first match, and I wouldn't leave till it was over. Those are probably my fondest memories, just sneaking into the nosebleed sections," Roddick recalled yesterday. "I actually snuck into the players' lounge one time and stole a cheesecake."

He still comes to Flushing Meadows at birthday time, nowadays as a competitor — and with a certain James Scott Connors tagging along as his coach.

Roddick turned 25 yesterday and marked the occasion by reaching the US Open's third round, although not before losing the opening set and moving on when his opponent, former XL Bermuda Open winner Jose Acasuso of Argentina, quit after the third because of a left knee injury.

"That's the good thing about Grand Slams: You get in the grind, and whoever doesn't mind the grind wins," Connors said after watching the match through silver wraparound sunglasses. "The way Andy played today, especially in the second and third sets, is always good. As long as he's playing the right kind of tennis, that's all that counts."

A trainer came out to wrap white tape above Acasuso's left knee after the second set, then added another bandage below the knee at the next changeover. By the end, he was as stiff and creaky as the Tin Man in "The Wizard of Oz," barely bending or moving at all, and the score was 4-6, 6-1, 6-2 when Acasuso decided he couldn't continue.

"I don't think you like winning matches like that," the No. 5-seeded Roddick said. "But at the end of the day, your goal is to get through."

In other words: no complaints. Same for Donald Young, the 18-year-old Chicago native who was 0-11 in tour-level matches until last week and never had won a Grand Slam match until this week.

Now he's in the Open's third round, and he didn't have to lift a racket yesterday, because his scheduled opponent, No. 13 Richard Gasquet, withdrew, citing a viral infection. Young saw Gasquet practice and saw him in the locker room, so assumed they'd be playing.

"Prefer to win it," said Young, who faces Feliciano Lopez next, "but I'll take this."

Gasquet, who came back to upset Roddick in the Wimbledon quarter-finals after dropping the first two sets, said he had a fever and a sore throat.

"With my illness," the Frenchman said, "I'm sure I can't win this match."

Roddick, among others, was surprised.

"I feel like that's a short-term thing. I'd probably go out there and give it a go," Roddick said. "My biggest thing with playing matches versus not playing matches is if you're risking long-term — if it's going to affect you longer than just that day or a week or two down the road."

No. 2 Rafael Nadal had to make that sort of decision before playing Wednesday, when he was far from his best while dealing with tendinitis in his left knee. Like Acasuso, he grew up playing more on softer clay courts than the cement-like hard courts of the US Open — and both thought that might have been a factor in their injuries.

Players who had to earn victories yesterday included No. 4 Nikolay Davydenko, No. 9 Tomas Berdych and No. 19 Andy Murray, while unseeded Lee Hyung-taik knocked off No. 14 Guillermo Canas in straight sets. There were no significant surprises in women's action, where 1997 champion Martina Hingis got past Pauline Parmentier 6-2, 7-5, and 2004 champion Svetlana Kuznetsova had to work a little harder to defeat Camille Pin 6-3, 4-6, 6-0.