Hingis advanced to the quarterfinals at the $520,000 Acura Classic tonight with a 6-1, 4-6, 6-3 victory over American Lisa Raymond.

Seeded second in this event behind American Lindsay Davenport, Hingis reclaimed the top spot in the WTA rankings when Davenport lost to Venus Williams in the semifinals of last week's TIG Tennis Classic in San Diego.

On Sunday, Hingis put an exclamation point on her return to the No. 1 ranking with a convincing victory over Williams in the final to capture her WTA Tour-leading fifth title of the year.

Hingis, 18, suffered back-to-back defeats at the French Open and Wimbledon and took a temporary break from the game. But she looked impressive in her return to the tour last week as she never lost a set en route to the title.

Raymond celebrated her 26th birthday on Tuesday with a 6-3, 6-1 first-round victory over Wimbledon semifinalist Mirjana Lucic of Croatia. A former NCAA champion, Raymond upset Hingis in Zurich, Switzerland two years ago, one of only five losses Hingis suffered in all of 1997.

Earlier today, third seed Mary Pierce of France avenged last week's first-round loss to Japan's Ai Sugiyama in San Diego by posting a 6-3, 7-5 victory.

Also, fourth seed Arantxa Sanchez-Vicario of Spain stormed past Romania's Ruxandra Dragomir, 6-3, 6-1; sixth-seeded American teenager Serena Williams dumped Switzerland's Patty Schnyder, 6-3, 6-1; and Julie Halard-Decugis of France got past 1994 champion Amy Frazier of the United States, 7-6 (7-5), 7-5.

Pierce will face Halard-Decugis and Sanchez-Vicario will battle Serena Williams in Friday's quarterfinals.

First prize is $80,000.