Henman squandered four match points in the third-set tiebreak as the top-seeded Agassi gutted out a 7-5, 1-6, 7-6 (12-10) victory at the $5.725 million event.

On the women's side, top seed Martina Hingis of Switzerland moved one step closer to a possible showdown with Lindsay Davenport for the No. 1 ranking as she dumped 18th seed Amanda Coetzer of South Africa, 6-3, 6-1, tonight.

Hingis, who improved her season record to 24-3, will meet seventh seed Monica Seles in the semifinals on Thursday. A two-time champion, Seles stormed past No. 19 Amy Frazier, 6-0, 6-3, in an all-American matchup earlier today.

Henman, the 10th seed from Britain, got his first match point at 6-5 in the tiebreak, but he netted a volley on his first chance to close out the match. After Agassi failed on his first match point at 7-6, he hit a forehand long to give Henman his second match point at 8-7. But the American hit a backhand, crosscourt winner to stay alive.

A lunging volley winner by Henman set up his third match point at 9-8 and his first opportunity to close out Agassi on serve. But Henman committed a crucial double fault, his 11th of the match, to give Agassi another chance.

"All of a sudden, you get a little life because you feel like you're dealing with the circumstance," Agassi said. "You are a little relieved."

Agassi gave Henman his fourth match point after hitting a forehand long, but Henman hit a backhand long, tying the tiebreak at 10-10.

Agassi got his second match point of the tiebreak after a backhand winner and finally closed out the 2 1/2-hour match when he hit a brilliant backhand, crosscourt return off Henman's second serve.

"I won more games. I probably won more points," Henman said. "At the end of the day, I suppose I didn't win the most important ones. I think the frustration of losing is the overriding feeling."

Henman fired 14 aces but committed 42 unforced errors as he fell to 1-2 lifetime against Agassi.

Agassi, a three-time champion, has turned things around this week after entering the event on a two-match losing streak. He won his first three matches in straight sets before pulling out today's win, his 38th at this event.

"I'm stepping it up as I go along," Agassi said. "That comes from getting these matches in. I'm in position to play my best tennis. I don't feel like it's happened yet."

In tonight's other men's quarterfinal, No. 6 Gustavo Kuerten of Brazil meets unseeded Wayne Ferreira of South Africa.

On Thursday, two-time winner Pete Sampras of the United States, the second seed, meets No. 9 Nicolas Lapentti of Ecuador, and red-hot Australian teenager Lleyton Hewitt, the 14th seed, faces unseeded Jan-Michael Gambill of the United States.

Hingis broke Coetzer six times as she won for the fifth straight time and seventh in nine meetings overall with the diminutive South African. She must fare better than Davenport at this event to retain the top ranking, which she has held for a total of 134 weeks.

Davenport will put her 18-match winning streak on the line Thursday against No. 12 Sandrine Testud of France in the other semifinal.

First prize for the men's champion is $410,000. The women's winner pockets $350,000.