Wheaton Too Good for Lendl : Tennis: He upsets the world’s third-ranked player to join three other Americans in semifinals of $6-million tournament.

David Wheaton used a powerful serve and an aggressive game to upset Ivan Lendl, 6-2, 7-6 (7-4), Friday to reach the semifinals of the $6-million Grand Slam Cup.

Wheaton, a 21-year-old second-year pro ranked 27th in the world, dominated from the first point to overpower Lendl of Czechoslovakia, the world’s third-ranked player and the top seeded player remaining in the richest tournament in tennis history.

His victory in 1 hour 27 minutes made it certain that it will be an all-American final.

Earlier, Brad Gilbert outlasted Aaron Krickstein in an error-filled match to win, 6-7 (7-5), 6-4, 6-3.

In today’s semifinals, Gilbert will play Wheaton, and Pete Sampras will face Michael Chang.

“This is the biggest win of my career,” Wheaton said. “I had a simple strategy and that was to hit as deep as I could and to try to keep him under pressure.”

Wheaton broke Lendl in the opening game to set the tone of the match.

Wheaton scored another break for a 4-1 lead, dropped his serve in the next game, but broke again to lead, 5-2. Wheaton served out the set at love.

There were no breaks in the second set, but Wheaton was down 15-40 in the fourth game.

“He hit an ace with his second serve, then an unreturnable serve, then another ace. He served himself out of trouble,” Lendl said.

Lendl himself fought off two break points in the ninth game.

Wheaton, seeded eighth, raced to a 3-0 lead in the tiebreak and had two match points. Lendl saved the first with an effective return to the corner, but his next return went long.

“The court is fast and favors his game,” Lendl said. “He took full advantage of it. I knew he can hit powerfully, but I was surprised how consistent he was. He deserves to be in the semifinal.”

By getting to the semifinals, Wheaton made sure of winning at least $450,000, nearly doubling his career earnings of $481,712.

Gilbert, ranked 10th in the world, was also happy about the money.

“This is about three times more money than I ever made in a week and I feel great about it,” said Gilbert, who only came to the tournament as a replacement for injured Andre Agassi. “And I can still make more.”