It is a cold, unbending wind that blows any champion out of a Grand Slam tournament and yesterday its name was Karol Kucera. Under Melbourne's pin-bright night skies, the 23-year-old Slovak swept away Pete Sampras, the world's finest player, in four sets 6-4, 6-2, 6-7, 6-3.

This was remarkable. For Sampras, the number one seed and holder of the Australian Open title, had appeared the one constant in an ever-changing and swirling firmament here.

The only danger in his path to the final appeared to be Petr Korda of the Czech Republic, who last year beat him in the fourth round of the US Open, and who earlier in the day set up a putative semi-final against the American after a strenuous five-sets victory over Sweden's Jonas Bjorkman, the number four seed.

Kucera's chances of causing an upset had been scarcely considered, although these days Sampras usually struggles in one of his matches during a Grand Slam. Prior to this game, all had been pretty much sweetness and light, a potent warning in itself.

Kucera, ranked number 20, had never previously managed to get beyond the third round of a Grand Slam, yet began this quarter-final as if defeat had never for an instant crossed his mind.

He started to break the previously omnipotent Sampras serve with something bordering on the commonplace. Sampras could not believe it and neither could the crowd. Kucera, on the other hand, appeared mildly surprised whenever he failed.

"In this situation you hope something will crack and nothing did," said Sampras, who at the end refused to shake hands with the umpire, Lars Graff of Sweden, who overruled a couple of calls in Kucera's favour. Not that they were really crucial, as Sampras admitted later.

So Kucera will now play Korda, a political border having separated them since their birth in Czechoslovakia, although they both now live in Monte Carlo. What must be worrying Sampras is a boundary of a different kind - that between him and a burning ambition to win more grand slams than anybody else in modern times.

Currently he has 10, one behind Rod Laver and Bjorn Borg, and two behind Roy Emerson. But all the time it is getting tougher. Of the last nine played he has now won three, and has gone out before the semi-finals on five occasions. "These guys like Kucera have nothing to lose," he said. True, and more and more are lining up.

When Korda walked out of his quarter-final against Bjorkman in the US Open last year, having also sensationally defeated Sampras in the previous round, the cry went up that the Czech player had lost his nerve or, in sporting parlance, bottled it.

Korda is a man of complex temperament who appears to spend the majority of his life, like Mr Bean, making the wrong decisions at crucial times. Even yesterday, after defeating Bjorkman he claimed that he had managed to get his preparation all wrong.

The lean left-hander, who eschews weight training for fear of ripping his slender body to sinewy bits, has never hit the Grand Slam heights his talent has undoubtedly warranted.

That miserable defeat by Bjorkman at Flushing Meadows when Korda threw in the towel at 7-6, 6-2, 1-0 down was blamed on a head cold. Nobody much believed it at the time, and said so.

"That hurt," said Korda yesterday after defeating the Swede 3-6, 5-7, 6-3, 6-4, 6-2. "But today I feel as if I have gone from the bottom of the river to the high mountains."

When Venus Williams bounded to a 16 minute first-set lead over fellow American and second seed Lindsay Davenport, the odds on her reaching a second a successive grand slam final appeared very short. But in a match of little or no subtlety Venus was eventually out-clobbered 1-6, 7-5, 6-3. It was a harsh lesson for the 17-year-old, but one she must heed.

The match was an embarrassing battle to see which player could hold her serve as five successive games went against serve in the second set. There were another five breaks in the third, but Davenport was the more consistent and became increasingly dominant at the net.

"I think in the first set I played practically perfect tennis with almost no errors. But it's not the easiest thing to keep up such a game," Williams said. "In the future I don't plan to be broken ever again."

Davenport, who has never reached a grand slam final, now faces Conchita Martinez in the semis, the Spaniard defeating France's Sandrine Testud 6-3, 6-2.