Seeking her fourth title here in five years, Hingis was closing in on a victory over Belgian qualifier Justine Henin when her opponent retired in the second set with an inflamed right foot. Hingis was leading, 6-3, 3-0.

Fourth seed Arantxa Sanchez-Vicario of Spain struggled in her second-round match with Cara Black of Zimbabwe before prevailing, 6-2, 3-6, 6-4.

Unseeded Kim Clijsters of Belgium followed up Tuesday's upset of sixth seed Anna Kournikova with a 7-6 (11-9), 6-3 win over Jana Kandarr of Germany.

Later today, fifth seed Amanda Coetzer takes on Patty Schnyder of Switzerland.

Hingis was two points away from defeating eventual champion Venus Williams in the U.S. Open semifinals, but lost four straight games to suffer a heartbreaking defeat. She did not represent Switzerland at the Olympic Games in Sydney, citing a hectic schedule that would not allow her to make the trip to Australia.

The 20-year-old Hingis has won five titles this season and has compiled a 59-9 record. She defeated Mary Pierce, 6-4, 6-1, in last year's final and also won this event in 1996-97.

After falling in the quarterfinals of the Olympics, Sanchez-Vicario is seeking her first title of the year. She reached the final at the Family Circle Cup and Betty Barclay Cup during the spring claycourt season.

The 28-year-old Spaniard is making her sixth appearance at this event, having advanced to the semifinals in 1992 and 1998.

In first-round action, eighth seed Dominique Van Roost of Belgium got past Anne Kremer of Luxembourg, 7-5, 7-6 (7-4); Asa Carlsson of Sweden downed Magui Serna of Spain, 6-3, 6-3; and Magdalena Maleeva of Bulgaria held off Sabine Appelmans of Belgium, 6-4, 5-7, 7-5.

First prize is $87,000.