NEW YORK -- Former champion Marat Safin battled his temper and some booming serves from Nicolas Kiefer to advance in the first round of the U.S. Open on Tuesday with a draining 6-3, 4-6, 4-6, 6-4, 7-6 (4) victory.

Safin smashed two rackets during the match, which lasted 4 hours, 31 minutes. In the end, the German gave in to fatigue and cramps.

It wasn't easy for Safin, the Open's 2000 champion and seeded second this year. He traded huge serves with Kiefer that exceeded 130 mph. Twice, Kiefer broke Safin's serve late to stay in the match, and another time Kiefer raced from one corner of the court to the other to save a point.

Both players were iced for cramps in their upper legs as the match neared the end. Safin was flat on the court being stretched while Kiefer sat in his chair as the trainer worked on him.

Limping badly, Kiefer twice saved match points and forced a tiebreak. But he collapsed on the court reaching for a shot at 3-5. He was helped to his feet and won the next point before the Russian ended the marathon.

"He tried as much as he could,'' Safin said. "It was unbelievable.''

Safin had 15 aces and 64 unforced errors to 12 aces and 59 unforced errors for Kiefer. Twelve double faults hurt Kiefer's chances for the upset.

In other action, defending champion Lleyton Hewitt advanced 6-2, 6-3, 6-3 over Nicolas Coutelot, riding 14 aces to the victory.

No. 11 Andy Roddick was treated for a blister on his right hand during the final set but pulled out a 7-6 (2), 6-3, 6-4 victory over Dutch qualifier Martin Verkerk at night. Roddick had just 10 errors to 46 for Verkerk.

Carlos Moya, awarded his highest seed at the U.S. Open in three years at No. 9, advanced to the second round of the season's final Grand Slam by defeating Adrian Voinea 3-6, 6-4, 6-3, 7-6 (4).

The victory was a grind for Moya, a clay-court specialist who came into the Open after winning at Cincinnati -- just the second hardcourt title of his career. Ten of his previous 11 victories were on clay, and he won at Cincinnati by defeating No. 1 Lleyton Hewitt in the final.

Former finalist Mark Philippoussis, hounded by knee trouble, was forced to retire from his match against No. 24 Sjeng Schalken after winning the first two sets.

Moya came into the Open with four titles this year, tying Andre Agassi and Hewitt for the most on the tour. It's the first time since 1995 that Voinea has lost in the opening round of this tournament.

Philippoussis, runner-up in the Open in 1998 but unseeded now and battling a cranky left knee, looked strong for two sets against Schalken. But after losing the third, the Australian fell in a heap on an overhand and came up grimacing as he gripped his left knee.

There have been three operations in 14 months on the knee, and Philippoussis was in obvious pain as ATP trainer Doug Spreen examined him. When Spreen asked how he felt, Philippoussis said, "I'm scared.''

The Australian struggled to his feet and, after Spreen worked on him, he was able to continue for a while, even winning another game. But on a changeover Spreen examined him again. "It hurts,'' he told the trainer. A few moments later, Philippoussis retired from the match, allowing Schalken to advance 6-7 (1), 4-6, 6-3, 5-3.

He left the grounds to get an MRI on his knee.

"All the players are praying not to get injured. Any small injuries -- even a finger, or some small muscles you don't even know about -- can bring you trouble,'' said Safin, who withdrew from a tournament in Indianapolis this month because of injured ribs. "Tennis is getting a little bit more powerful. We're playing much faster. That's why the body breaks.''