Pete Sampras and Brad Gilbert won their semifinals Saturday in the $6 million Grand Slam Cup, setting the stage for the richest match payoff in tennis.

Sampras downed Michael Chang in straight sets, 6-3, 6-4, 6-4 before Gilbert powered his way to the final with a 6-3, 3-6, 7-6 (9-7), 2-6, 6-4 victory over David Wheaton in a four-hour match.Wheaton, ranked 27th in the world, and Gilbert, rated 10th, were on the verge of fisticuffs after a much-disputed decision in the third set.

The winner of the Sampras-Gilbert match will earn $2 million. Each is already guaranteed $1 million. Chang and Wheaton collected $450,000 apiece for reaching the semifinals.

Gilbert, who defeated Wheaton for the fourth time, cruised in the first set, but Wheaton commanded the second set with strong first serves and brilliant volley-stops.

Both players had trouble with their first serves in the third set. Gilbert lamented his poor performance with loud shouts and at one point threw his racket on the floor in rage.

With the tie-break score 6-6 in Gilbert's favor, his volley triggered a lengthy dispute after the referee overruled the linesman, who had called the ball out.

After Wheaton lost the tie-break, the players exchanged angry shouts on the sideline and seemed poised to go after each other when an official interceded and seperated the two.

"It was just the heat of the moment," Gilbert said.

The crowd, clearly on Wheaton's side, refused to quiet down for minutes, which added to the already tension-loaded atmosphere.

The fourth set began with both players getting their serves through, but Wheaton broke Gilbert's serve in the fourth game with a back-hand return and again at 5-2 to wrap up the set.

Gilbert broke Wheaton's first serve when he stretched to reach a volley by his 21-year-old fellow American. The match drew on without Wheaton being able to make up for the early break.

Sampras needed 2 hours, 27 minutes to eliminate Chang, whose form paled to the one he showed earlier in the week while defeating world No. 1 Stefan Edberg of Sweden.