Hingis beat Alexandra Stevenson 6-1, 6-3. Williams, the defending champion coming off a surprising quarterfinal loss to Meghann Shaughnessy last week in the Bank of the West Classic, defeated Daja Bedanova of the Czech Republic 6-1, 6-3.

Third-seeded Jennifer Capriati and fourth-seeded Lindsay Davenport also advanced.

Capriati, the 1991 and 1992 winner, overcame a 1-3 deficit in the first set to beat 15th-seeded Jelena Dokic of Yugoslavia 6-4, 6-2. Davenport, the 1998 champion, edged Barbara Schett of Austria 6-1, 7-5.

Hingis took the first set in 20 minutes, then traded service breaks with Stevenson before taking the final three games in the second set of the 57-minute match.

``Whenever I had a chance, I stepped it up,'' said Hingis, the 1997 and 1999 winner. ``We played at Indian Wells two years ago when she was still a rookie. I know she is moving better now. She hits the ball hard, but sometimes with not enough control.''

The loss ended Stevenson's five-match winning streak -- her longest since winning eight straight en route to the 1999 Wimbledon semifinals.

In other matches, seventh-seeded Monica Seles beat Shaughnessy 6-4, 6-1; sixth-seeded Nathalie Tauziat of France edged 10th-seeded Magdalena Maleeva of Bulgaria 6-2, 5-7, 6-2; and 12th-seeded Sandrine Testud of France beat eighth-seeded Elena Dementieva of Russia 6-2, 6-4.

In doubles, Hingis and Russia's Anna Kournikova advanced to the semifinals, beating Alexandra Fusai and Rita Grande 6-3, 7-6 (1). Kournikova, recovering from a stress fracture in her left foot, is playing for the first time since February.