Defending champion Andy Roddick kept the home flag flying at the U.S. Open on Friday, but it was a bad day for his compatriots as only two American men reached the third round, their worst showing in tournament history.

Juan Carlos Ferrero and David Nalbandian were both beaten, while Lleyton Hewitt continued to impress but the best was saved for last as Roddick served up another awesome display under the lights at Flushing Meadow.

Second seed Roddick was at his most ruthless on Arthur Ashe Court as he beat Spanish teenager Rafael Nadal 6-0, 6-3, 6-4 in a second round match.

Roddick equalled his own U.S. Open record for the fastest serve with a 152mph bullet and such was the venom of his delivery that Nadal twice found himself on the floor after taking evasive action.

A loss of concentration at the start of the third set allowed the Spaniard back into the match with an early break, but Roddick broke back for 4-4 and then repeated the feat two games later to clinch victory.

"I felt like I played really well for the first two sets," Roddick said.

"I kind of had a concentration lapse at the start of the third set but I was able to come through in the end."

Roddick's victory was the only highlight for home fans in the men's event as Vince Spadea (23) and Jan-Michael Gambill were beaten.

Sixth seed and two-time champion Andre Agassi is the only other American left standing.

HEWITT CRUISES

Elsewhere, former champion Lleyton Hewitt bristled, battled and eventually blossomed on his way to a 7-6, 6-1, 6-2 victory over Moroccan Hicham Arazi.

Hewitt, who came into the tournament with back-to-back wins in Washington and Long Island, shrugged off a warning for ball abuse in the first set to overcome his tricky opponent.

"I wasn't as aggressive at the start as I was the other day," said Hewitt, who will meet Spaniard Feliciano Lopez in the third round .

"I played a poor service game (at 3-3) but I hung in there and I thought I stepped it up pretty well after that."

Ferrero said he wanted to forget 2004 after he was beaten 7-6, 4-6, 6-7, 6-2, 6-3 by Austria's Stefan Koubek.

The seventh-seeded Spaniard suffered with an adductor injury at the end of the third set and Koubek took advantage to secure the win.

Since reaching the semi-finals of the Australian Open in January, Ferrero has struggled with illness and injury and was beaten in the French Open second round and the third at Wimbledon. He has yet to win a title in 2004.

"It is (more) frustrating than you can imagine," Ferrero said. "I don't think I have played a tournament this year at 100 percent fit."

While Ferrero's defeat was not totally unexpected, comeback kid Tommy Haas upset the formbook when he beat 12th seed Sebastien Grosjean.

The German former world number two, who missed the whole of last season after shoulder surgery, came through 6-4, 6-4, 1-6, 6-1 to set up a third-round meeting with Brazilian qualifier Ricardo Mello.

Eighth seed Nalbandian became the second-highest seed to go out when he was beaten in five sets by Russian Mikhail Youzhny.

SERENA STRUGGLES

Elsewhere, Serena Williams, Amelie Mauresmo and Jennifer Capriati maintained order in the women's event by reaching the fourth round.

Third seed Williams opened the evening session in slightly more modest fashion than in her opening two matches, with the yellow low-cut shorts of French 16-year-old Tatiana Golovin putting the American in the shade.

Williams's game was also far from shining as she made 42 unforced errors, having to dig deep to come from 4-1 down in the first set on her way to a 7-5, 6-4 victory.

"Nearly 50 unforced errors in two sets, that's virtually giving away a set," said Williams, who now plays 15th seed Patty Schnyder. "I was going for far too much.

"There were shots that I really should have made. I was playing two opponents, her and myself."

Second seed Mauresmo stormed into the fourth round with a 6-2, 6-0 demolition of Venezuela's Maria Vento-Kabchi.

"I felt much more confident today than in my other matches," said Mauresmo, who is still looking for her first Grand Slam title. "I feel like things are coming together."

Capriati won the first set in 17 minutes against Vera Douchevina, but the Russian pushed the eighth seed hard before going down 6-0, 6-7, 6-3.

Russia's women continued to progress, with sixth seed Elena Dementieva and 10th seed Vera Zvonareva setting up a fourth-round showdown.

But there was disappointment for American teenager Angela Haynes, when she was beaten 6-3, 7-6 by 16th seed Francesca Schiavone of Italy.