We say that Andre Agassi can occasionally push his tennis beyond the limits and return with a match in his palm. We don't know where he goes. We don't always know how he does it. But he is there swatting balls that most players cannot see, defying the logic that a man cannot run 10 yards and return a ball at 135 mph.

Of all the players, it has been Agassi alone who has been able to disturb the monotonously familiar narrative of the modern grass game. He did so once again, yesterday, this time more breathlessly that we imagined he could, unmasking Mark Philippoussis in the process.

This match was given an early start because it had five sets and four hours stamped on the cover. Agassi polished it off in three sets, taking just under two hours. Pete Sampras, we believed, was contesting a three set match against the unseeded Jan-Micheal Gambill, but he struggled to finish in four sets. Pat Rafter cruised past German Alexander Popp and Vladimir Voltchkov brought his career to new heights. In beating Byron Black 7-6, 76, 6-4 Voltchkov becomes the first qualifier to advance to the semi-finals at Wimbledon since John McEnroe in 1977. In the Open era only three qualifiers have ever advanced to the semi-finals of a Grand Slam tournament and none have ever reached the final.

But it was Agassi who sparkled. Summing up his total suppression of the Philippoussis threat, he said: "I don't get distracted by people aceing me. I try to just make sure I do well with the opportunities I get, knowing that they are eventually going to come.

"There are a lot of things going on out there that help you get around one guy's particular weapon."

The first set required a tie break, with the two players locked at 6-6 before Agassi built two service breaks and hit an ace for the winner. While the Philippoussis serve was his obvious weapon, it was it's failure to work in the second set that wrested the match from his grasp. When he double faulted to allow Agassi to go a break up at 5-3, there was no way back, and the American emerged with a 7-6, 6-3, 6-4 victory.

Winning 20-18 in the fifth set in a previous round against Holland's Sjeng Schalken was certain to have affected the energy levels of the Australian, something he reluctantly acknowledged. "Well' I'm a little sore. That's something I knew was going to happen. There wasn't anything to be ashamed of the way I played. There were two breaks out there and that cost me the match. It was simple."

Pete Sampras, apparently undergoing acupuncture in an effort to keep his tendinitis under control, saw the future of American tennis in his opponent JanMicheal Gambill, the guy from Spokane, Washington with the movie name and film star appeal. Gambill took the second set off Sampras in a tie break before the typical gear shift upwards from the reigning champion, who won 6-4, 6-7, 6-4, 6-4.

"He was giving me a lot of problems with his serve. Got through some tough situations. But you're looking at the future of American tennis," said Sampras.

No doubt the same could be said of Voltchkov, who meets Sampras in the semi-final tomorrow. The Belarussian, who has been scrambling around for apparel and footwear, is a former junior champion who has yet to win a tour title. He arrived at Wimbledon without a clothing company sponsorship or any new clothes. The Adidas shorts he was wearing were given to him by Marat Safin.

He has not yet been out to a restaurant in London and is pressed to stay at home in a rented flat with his father, who does the cooking. So far Voltchkov is guaranteed £119,380 sterling, a figure which eclipses the combined amount of money he has earned to date.

Fittingly he faces the richest man in the game. In career earnings alone up until the beginning of this year, Sampras has scooped $38,808,161.

The right hander, who prefers the back of the court is simply riding his good fortune.

"It's a dream come true to play Pete. What else can you wish for? Before this the match (against Black) was a chance I felt I must take. Now it's just go out there and enjoy every minute."

Enjoying every day is Pat Rafter, who is wallowing in the painless exercise of going through a tournament without his shoulder grinding him to a halt. The career-threatening injury appears to have been mended by surgery undertaken last year and his results have shown as much.

Alexander Popp certainly felt that way, as the Australian once again engaged in a one-way tie, winning 6-3, 6-2, 7-6. He now faces Agassi.

Rafter has a big serve but also a more athletic all round game compared to that of Philippoussis.

"I slipped through the draw pretty quietly," said Rafter. "That's a very nice way of going through the draw, people not expecting much of you. I've played Andre a few times when he's had some really bad days. I just hope he has one."