PARIS - Venus Williams' celebrated corset went under wraps Sunday, and now it's out of the French Open.

Playing with a long-sleeve top over her black lace outfit, she lost in the fourth round to Nadia Petrova, 6-4, 6-3.

Williams came into the tournament seeded No. 2 behind her sister Serena, but Petrova spoiled the possibility of a sibling showdown in the final.

"I'm obviously disappointed," Williams said. "I feel like I had a day where I wanted to hit the ball crosscourt and it went down the line. It just wasn't a good day."

Petrova has been a nemesis for the Williams family lately - she beat Serena in the third round at Madrid less than three weeks ago.

"Today's match was just about going out there and performing my best," Petrova said. "I was mentally focused, and I kept my nerves calm."

Justine Henin rallied in a winner-take-all set that seemed like a final, outslugging Maria Sharapova, 6-2, 3-6, 6-3. The two former No. 1s returned to center court following an overnight suspension of the third-round showdown after two sets.

In men's play, top-ranked Roger Federer reached the quarterfinals in his bid for a second successive title, beating Olympic doubles partner Stanislas Wawrinka, 6-4, 7-6 (5), 6-2.

Federer will next play No. 5-seeded Robin Soderling in a rematch of last year's final. Soderling advanced by beating No. 10 Marin Cilic, 6-4, 6-4, 6-2.

No. 4 Andy Murray was upset by No. 15 Tomas Berdych, 6-4, 7-5, 6-3. Berdych will next play No. 11 Mikhail Youzhny, who advanced when No. 8 Jo-Wilfried Tsonga retired with a hip injury trailing, 6-2.

Berdych and Youzhny are first-time Roland Garros quarterfinalists.

Joining Petrova in the women's quarterfinals were No. 3 Caroline Wozniacki, No. 5 Elena Dementieva, and No. 17 Francesca Schiavone.

On a damp, windy afternoon, Petrova and Williams bundled up. Only the flounce of Williams' buzz-generating corset was visible, while Petrova wore long sleeves and tights under a frilly skirt.

The Russian controlled rallies with steady play from the baseline and finished strong. Petrova swept the final four games and wobbled only once, shanking an overhead when leading, love-30, in the final game.

She collected herself and won the final two points, closing out the match with an emphatic forehand winner.

"I don't think she did anything super special, but I think she just played a little bit more consistently," Williams said. "The conditions aren't that easy with the rain and the wind."

Williams converted only one of seven break-point chances. In the second set she lost serve three times after taking a 2-love lead.