PARIS - Needing one point for an upset win over Justine Henin at the French Open, Sam Stosur wavered, hitting a double-fault.

The Australian took a deep breath and tried again. This time, she launched a confident serve into the corner, setting her up for an overhead slam to seal the biggest victory of her career.

Stosur sidelined Henin, 2-6, 6-1, 6-4, in the fourth round Monday, ending the four-time French Open champion's streak of 24 consecutive victories at Roland Garros.

Stosur's opponent in the quarterfinals will be top-ranked Serena Williams, who beat Shahar Peer, 6-2, 6-2.

"Obviously, beating Justine is going to give me lots and lots of confidence," said Stosur, seeded No. 7. "It's a great achievement for me, but it's not over yet. I'm just in the quarters and going to play the No. 1 player in the world next."

Another four-time champion, Rafael Nadal, advanced by beating No. 24-seeded Thomaz Bellucci, 6-2, 7-5, 6-4. Nadal, who lost in the fourth round in 2009, has yet to drop a set this year and will next play fellow Spaniard Nicolas Almagro, seeded 19th.

No. 3-seeded Novak Djokovic eliminated the last American in the men's draw, beating Robby Ginepri, 6-4, 2-6, 6-1, 6-2.

No. 4 Jelena Jankovic and unseeded Yaroslava Shvedova won in straight sets and will meet in the quarterfinals.

Henin's defeat was her first in the tournament since 2004. She was seeded 22d playing at Roland Garros for the first time since ending a 20-month retirement, and looked like a title contender in the early rounds.

"I just wanted so much that the adventure could keep going," she said.

But after taking a 4-3 lead in the final set against Stosur, Henin showed signs of nerves and was betrayed by her elegant backhand.

Serving at 4-all, the Belgian double-faulted to reach break point, then yanked a backhand wide. In the final game, she pushed three backhands into the net, including a potential put-away on the first point.

In the final two sets, Stosur had a 20-8 edge in winners and converted four of five break-point chances.

"I knew what I had to do," she said. "I kept going for it and I believed in myself."

As for that double-fault on the next-to-last point?

"I just tried to shake it off and tried to have a laugh at myself, not worry about it and get the next one in," Stosur said.

The 26-year-old Stosur has won 18 matches on clay this year, the most on the women's tour. A Roland Garros semifinalist last year, Stosur has a career-best ranking at No. 7, the highest for an Australian-born woman since Wendy Turnbull in 1985.

Williams advanced easily, looking shaky only after her fourth-round victory, when she tried to speak French to the crowd.

"I get so nervous," she told the interviewer with a giggle in English when she was done. Otherwise, she advanced smoothly to the quarterfinals.

"I seem to always be able to turn it up during this particular stage," Williams said. "Hopefully I turn it up again."

She complained of dizziness from a cold after a seesaw three-set win in her previous match, but the only wobble against the No. 18-seeded Peer came at the start. Williams lost the first seven points, then swept nine in a row.

From 2-all, Williams won five consecutive games to take charge of the match.