WIMBLEDON: Windy and cold, the covers rolled on with the usual military precision for the first time at 4:40 yesterday afternoon. And, with the weather, came cold winds for British number one Tim Henman, who unconvincingly advanced.

Henman did it the hard way in five sets in a wildly oscillating match on Court One, finally winning 7-6, 6-7, 4-6, 6-3, 6-2.

The fourth seed won the first set, accepting three double-faults to come back to 5-5 and then taking the early lead on a tie-break.

But Kratochvil replied by taking the next two sets as Henman's game strangely deserted him, particularly after the rain delay in the third set when Kratochvil came out and broke Henman twice.

Only intermittently did the fourth seed, who had treatment throughout the latter stages of the match, trouble his unseeded opponent and never did he have him on the ropes despite it being the Swiss player's first ever appearance in a Grand Slam round of 16.

By the fifth game of the fifth set, Kratochvil had already handed Henman 17 double-faults while the favourite had, almost self destructively, converted only five out of 20 break-points.

But he survived, more out of gritty determination and an evident tightness creeping into his opponent's game.

Physically and emotionally it was tough, but Henman is through to face the unfancied Brazilian Andre Sa in the quarter-final.

Fortunately, that match takes place on Wednesday, giving Henman two days to recover for his sixth quarter-final in nine appearances.

"I was struggling a bit just before the delay. I'd a problem with my stomach and I'd not a lot of energy," said Henman afterwards. "The crowd can take a lot of credit for keeping me alive."

More satisfying for Australian Lleyton Hewitt was the fact that he unfussily came through against Russia's Mikhail Youzhny in straight sets, had his shower, completed his interviews and left for home before the first cloud emptied its load over south west London.

The number one seed is now to face Holland's Sjen Schalken in the quarter-final in his first ever time reaching this stage of the competition.

It illustrates the unusual nature of this year's championships. Hewitt is favourite to win, despite the fact that he has only ever reached the fourth round in four previous visits.

The field remains one largely twisted out of shape by the events of last week's black Wednesday, when the seeds tumbled.

There were no American men in yesterday's fourth-round matches for the first time in 80 years and those who advanced before the weather hit are scarcely household names.

Schalken from Holland, Brazil's Sa, a country where they have three grass-courts, none of which he uses, Argentina's David Nalbandian and Nicolas Lapentti from Ecuador are all sure of taking away a cheque for at least £68,250 as quarter finalists.

With Lapentti and Nalbandian's wins, South America is guaranteed a men's singles semi-finalist for only the second time in Wimbledon history, as the players face each other in the quarter-finals.

The only previous South American semi-finalist was Peru's Alex Olmedo in 1959. He went on to become champion, defeating Rod Laver in a three-set final.

But it is Hewitt's form that has captured most attention. The 21-year-old arrived at Wimbledon fresh from claiming his third successful title at Queens.

It puts him in joint second place behind Sampras in the list of career grass titles. He shares that position with fellow Aussie Patrick Rafter, who is currently taking a break from tennis.

"I played Schalken at the French in the third round. After the press conference, the Dutch journalists said he'd never been past the third round in a Slam. I found that pretty surprising," said Hewitt.

"I don't know why guys like Nalbandian, Lapentti are coming through. I'm not sure. If you return well and you stay aggressive from the back of the court and you pass well, then I don't think there's any reason why the baseliners shouldn't do that well."

And, clearly, they are.