Czech Petr Korda dethroned defending champion Pete Sampras in a five-set thriller, to send the number one seed and the world's top-ranked player tumbling out of the US Open. Korda, the 15th seed who lost his only Grand Slam final at the 1992 French Open, denied Sampras, who also won here in 1995, a chance for his third Grand Slam title of 1997 with a 6-7 (4/7), 7-5, 7-6 (7/2), 3-6, 7-6 (7/3) triumph.

Sampras, pushed to break point only twice in his three previous matches, surrendered three service breaks in 12 attempts against Korda in the match which lasted three hours and 37 minutes.

With the match poised at two sets each and 6-6, Korda soared to a 4-0 lead in the tiebreaker after Sampras blew three backhands and Korda followed with a backhand winner. Korda hit an ace for a 5-1 edge and when Sampras double faulted two points later, he had four match points.

Korda won it on the second with a service winner, then grabbed his head in an expression of disbelief. A minute later he did his trademark scissors kick in celebration.

Sampras, the reigning Wimbledon and Australian Open champion will now have to wait until next year for a chance at his 11th career Grand Slam title, which would put him one shy of Roy Emerson's all-time record.

"As far as this year, it's kind of over for me. There's nothing out there for me until the Australian Open," Sampras said. "It's just a lot of prize money. It's really disappointing."

Korda could have eliminated Sampras had he but taken advantage of three break points against Sampras while leading 6-5 in the first set.

Instead, Sampras responded with an ace and two service winners to reach deuce. He held to force a tiebreaker, then fell behind Korda 42 before Sampras took the next five points and the set.

Sampras double faulted on break point to give Korda a 3-2 lead in the second set and the Czech rode the break to even the match.

The third set went with serve to the tiebreaker, in which Sampras's only two points came with aces of 129 and 125 mph. Korda won seven of the final eight points, winning when Sampras hit a forehand into the net.

Rain halted play briefly in the second and third sets but showers forced a break of more than an hour after Korda held serve in the first game of the fourth set. Sampras took command when play resumed, breaking Korda's next serve to pull ahead 3-1 and breaking again in the final game to force a fifth set.

Sampras survived a similar epic match in the quarter-finals here last year, saving one match point before rallying to beat Spain's Alex Corretja 7-6, 5-7, 5-7, 6-4, 7-6, but this time it just wasn't to be.

Korda now advances to a quarterfinal against 17th ranked Swede Jonas Bjorkman, who beat 66thranked Australian Scott Draper 6-3, 6-3, 1-6, 7-6 (8/6).

Meanwhile, Greg Rusedski became the first British player to reach the quarter-finals of the US Open since John Lloyd 13 years ago with a convincing 7-6, 6-2, 6-2 victory over Daniel Vacek of the Czech Republic.

Prior to these championships Vacek had lost in the first round of his seven previous Grand Slams and has had little to write home about in other ATP events this year. And once he had lost the crucial tie-break 7-2, Vacek noticeably began to mutter and fret at the back of the court. Rusedski's serve is a mightily potent weapon - twice yesterday he crashed the ball down at 140 mph, and he has now chalked up 65 aces in his four matches without dropping a set - but his all-court game, under the tutelage of the American Brian Teacher, has improved remarkably this year.

So Rusedski now faces his second successive Grand Slam quarterfinal, having reached the last eight at Wimbledon for the first time before losing to France's Cedric Pioline.

Rusedski had expected to meet Mark Philippoussis in the fourth round, but Vacek managed to get the better of the huge-serving Australian, and clearly hoped to deal with Rusedski's serve in similar fashion. It was not to be. The British player is learning all the time to vary his serve, and on many occasions Vacek was defeated by the slice and accuracy rather than the sheer speed.

Similarly on his return Rusedski did not try to go for everything, being prepared to block Vacek's serve and force the Czech into errors which came thick and fast once he had lost the first set.

Chris Evert, the six-times US Open champion and darling of the New York crowds, believes there are only three women who can win this year: Martina Hingis, Monica Seles and Lindsay Davenport.

Davenport, still only 21, is an enigma. Three years ago she reached the quarter-finals at the Australian Open and Wimbledon but she has never progressed beyond the last eight in a Grand Slam since. Yesterday, in the fourth round, she pulverised Spain's Magui Serna 6-0, 6-3 and now meets Jana Novotna.

Women's world number one Hingis, seeking her third Grand Slam title of 1997, beat 40th-ranked Florencia Labat of Argentina 6-0, 62. Hingis next faces doubles partner Arantxa Sanchez Vicario, the 10th seed from Spain who routed Australia's Rachel McQuillan 6-1, 6-2.