KEY BISCAYNE, Fla. (AP) - On match point, Martina Hingis served, charged forward and smacked a volley into net. She stared at the ball and kicked it in mock frustration, then broke into a big grin.

Hingis had plenty of margin for error, and she won the next point to beat Barbara Schett 6-1, 6-1 Wednesday in the quarterfinals of the Lipton Championships.

The world's top-ranked player has looked first-rate at Key Biscayne, losing just 11 games in four matches. Hingis' latest victory took just 43 minutes, meaning her workday was over before 2 p.m.

``I love it,'' she said. ``You can go do something else if you know you played a great match. I'm going to have a massage.''

In the men's quarterfinals, Francisco Clavet beat Nicolas Kiefer 7-5, 6-3 and Sebastien Grosjean won a battle of unseeded players by beating Dominik Hrbaty 6-3, 5-7, 6-1. For the first time in the Lipton's 15-year history, there will be no Americans in the men's semifinals.

Hingis' opponent in the semis will be the winner of Wednesday night's match between Serena Williams and Amanda Coetzer. Possible opponents in the final Sunday are second-ranked Lindsay Davenport, No. 4 Jana Novotna, No. 6 Venus Williams and No. 7 Steffi Graf.

``Nobody can say who is going to win this tournament,'' Schett said.

Don't discount Hingis. At 18, the Swiss miss is no longer the freshest face on the WTA Tour, and teen-agers Amelie Mauresmo and the Williams sisters are among those challenging her reign.

But Hingis, who leads all players with 21 victories this year, returned to No. 1 last month. She beat Mauresmo in the final of the Australian Open for her fifth Grand Slam title and her first in a year.

Last year, Hingis lost in the semifinals of the French Open, Wimbledon and the U.S. Open, then lost the No. 1 ranking to Davenport. Chastened, she prepared for 1999 by training with Nick Bollettieri in Bradenton, Fla.

``That was the first time after a long time that I really worked for two weeks, day after day, three or four hours of tennis,'' she said. ``I lost some weight, and that was like the best thing I could do. You stop growing, and you start growing to the side.''

Fit and trim again, Hingis has regained her remarkable sense of anticipation. Her serve and forehand, meanwhile, are more powerful than before.

``You can see it,'' she said. ``I mean, I'm back to No. 1. The scores tell it.''

Results against Schett suggest considerable recent improve. Hingis needed a third-set tiebreaker to beat the Austrian at Sydney in January. Wednesday's match was rout.

``I was a much better player today,'' Hingis said. ``I took her much more seriously than I did in Sydney. I was always one point better.''

That will be the goal the rest of the week.