If world number one Kim Clijsters is going to reach her first US Open semifinal, she is going to have to overcome the woman who ousted her here last year -- France's Amelie Mauresmo.

Belgium's Clijsters defeated 21st-ranked American Meghann Shaughnessy 6-2, 6-4 while fifth seed Mauresmo ousted Thailand's Tamarine Tanasugarn 6-2, 6-2 to book a quarterfinal showdown at the year's final Grand Slam event.

Mauresmo beat Clijsters 4-6, 6-3, 7-5 in last year's US Open fourth round and has split four matches with Clijsters, not counting a Mauresmo injury retirement in 2001.

"I feel better this year than I did last year," Clijsters said. "But I really feel against Amelie everything has to be at your best. She can be real aggressive and with the slice and spin ball. She can really make it hard for you and make you adjust all the time.

"I can't worry if I'm not playing well. I have to stay mentally strong and stay motivated out there."

The 20-year-old girlfriend of Australian former men's number one Lleyton Hewitt made her best US Open run getting to the 2001 quarter-finals and she has reached the semis in 14 of 15 2003 events entering the Mauresmo match.

"We've played each other a lot already. We know each other's game pretty well," Mauresmo said. "She has some weapons to disturb me and I have a few to disturb her also."

Clijsters has 71 triumphs in 2003, the most by a woman at this stage of the season since Chris Evert in 1974. She was won a tour-best six titles this year. But to stop being the only women's number one without a Slam title, Mauresmo must go.

"We have had some unbelievable matches," Clijsters said. "It's going to be a tough one. She serves well. She doesn't make many unforced errors. I'm going to have to play my game very well if I want to have a chance to beat her."

Third seed Lindsay Davenport defeated Russia's 19th-ranked Nadia Petrova 6-0, 6-7 (6/8), 6-2 to reach her seventh US Open quarter-final in a row and will face a foe who has never beaten her, Argentina's 25th-ranked Paola Suarez.

But that's a problem. Davenport was limping by the finish of the Petrova match, favoring the two nerve-damaged toes on her left foot that forced her to pull out of a WTA final a week ago.

Monday finds second seed Justine Henin-Hardenne, who beat Clijsters in the French Open final, playing Russian teen Dinara Safina and American sixth seed Jennifer Capriati facing Russia's Elena Dementieva for quarterfinal berths.

Then Clijsters' revenge bid takes center stage.

Clijsters points to match toughness this year as a major reason why she is better prepared for the test offered by Mauresmo, who seeks her first Slam final since her 1999 Australian Open breakthrough.

Davenport cannot say the same. She took a cortizone injection to numb her pain last week and plans to have surgery after the Open, but hopes to make a stand, lierally and figuratively.

Petrova, a French Open semi-finalist, made 50 unforced errors to 33 for Davenport, spraying shots at the finish as Davenport took a conservative mode.

Davenport is the only past US Open champion still in the field by virtue of her 1998 title here.

Suarez eliminated Russia's 36th-ranked Elena Likhovtseva 6-2, 3-6, 7-5 in a match of 27-year-olds each trying to match their best Slam showing. Suarez lost her first four meetings with Likhovtseva but won her second in a row.