PARIS — Rafael Nadal's unbeaten run at the French Open is over.

The four-time defending champion lost in a stunning upset to Robin Soderling of Sweden 6-2, 6-7 (2), 6-4, 7-6 (2) today in the fourth round, ending the Spaniard's record 31-match winning streak at Roland Garros.

Soderling, seeded 23rd at this year's tournament, ran Nadal ragged on center court with his hard serve and booming forehand.

"When one player plays bad, (he) must lose," Nadal said. "(It) was my fault. ... I didn't play my best tennis and for that reason I lose."

Nadal has dominated the French Open since his first match on the red clay at Roland Garros. In his 31 previous matches, he had lost only seven sets — the last one coming against Roger Federer in the 2007 final.

"I played well today, but I think I played some even better matches in my career," said the 24-year-old Soderling, who called Nadal "the greatest clay-court player of all time."

"I worked good with my forehand, and my backhand worked well, as well. I worked my backhand flat and tried to go around and hit my forehand. I think I played exactly the way I wanted to play before the match. I served well, extremely well, and that really, really helped me today."

Defending women's champion Ana Ivanovic also lost, while top-seeded Dinara Safina advanced to the quarterfinals with another easy win. Maria Sharapova joined her with a fourth straight three-set win.

Also on the men's side, No. 3 Andy Murray of Britain, No. 10 Nikolay Davydenko of Russia and No. 12 Fernando Gonzalez of Chile made the quarterfinals.

Soderling finished with 59 unforced errors, more than twice as many as Nadal's 28, but the Swede's 30 forehand winners made up some ground on the top-ranked Spaniard.

"He didn't surprise me because I know how he plays and how dangerous he can be," said Nadal, who said he failed to attack Soderling. "I didn't play aggressive."

The crowd at Court Philippe Chatrier was split, many cheering for Nadal to continue his record run but others supporting Soderling.

"Maybe at one stage they supported Soderling more than me, and that was a bit sad," Nadal said. "But I wish when I'm back they can support me a bit more in key moments."

Nadal and Soderling played three times previously, with the Spaniard winning all three. But the middle match, which came in the third round at the 2007 Wimbledon tournament, was easily the most contentious.

That match took five days to complete — from when the pair first stepped on Court No. 1 to warm up — due to rain and the traditional middle Sunday day off. Things got heated when Soderling, who also tugged at the back of his shorts to mimic Nadal at one point, pumped a fist instead of offering a customary "sorry about that" wave after winning a point on a net cord.

In the second-set tiebreaker Sunday, Nadal hit the tape with a backhand and the ball toppled over to give him a 5-0 lead. Instead of just a quick wave, Nadal held both arms up to apologize.

On Sunday, Soderling wouldn't be goaded into saying anything bad about Nadal.

"I've been answering these questions now for two years. I mean, I'm feeling pretty tired of this," Soderling said. "He's just another player on the tour."

The last time two defending champions lost in the same round at a Grand Slam tournament was in 2004, when Justine Henin and Juan Carlos Ferrero lost in the second round of the French Open. Only four times in the Open era have both defending champions failed to reach the quarterfinals at Roland Garros.

Nadal had won three of the last four major titles, missing out only on the U.S. Open. After winning the Australian Open, he had a chance to complete a Grand Slam this year.

Defending his Wimbledon title will be Nadal's next major goal, but that will come after a little rest and relaxation.

"Right now, my preparation is for the swimming pool at my house," joked Nadal, who was also trying to become the first man to win five straight French Open titles. "Give me three more days."

The draw has now opened up for three-time finalist Federer. The former No. 1 needs only to win the French Open title to complete a career Grand Slam, and his road got clearer Saturday when potential semifinal opponent Novak Djokovic was eliminated.

The eighth-seeded Ivanovic did little right on Court Suzanne Lenglen, converting two of five break points and making 20 unforced errors in a 6-2, 6-3 loss to Victoria Azarenka of Belarus.

Before the final game of the first set, Ivanovic called for a trainer to look at her neck. Azarenka then held to take the lead, and broke Ivanovic's serve in the first and third games of the second set to take a 4-0 lead.

"I just suddenly started feeling so dizzy, and I completely lost my balance," said Ivanovic, who won her only Grand Slam tournament title at last year's French Open.

"Ever since then it was really hard. I struggled with looking up. I started feeling very dizzy, and I was struggling a little bit to find my balance."

The 19-year-old Azarenka lost in the fourth round at Roland Garros last year, and will next be playing in the quarterfinals of a Grand Slam tournament for the first time.

Safina had a much easier time on center court, advancing to the quarterfinals with a 6-1, 6-0 win over Aravane Rezai of France.

The top-seeded Russian won 11 straight games to close out the match. She has lost only five games through four rounds, and has won four of the eight sets she has played at love.

"It's really like five games that I lost before getting into the quarters," Safina said. "It's not a bad feeling, and I hope if I continue like this I can go a long way."

Safina took over the No. 1 ranking this year, but she has yet to win a Grand Slam title. She lost to Ivanovic in last year's French Open final, and fell to Serena Williams in this year's Australian Open title match.

Sharapova rallied again, this time beating Li Na of China 4-6, 6-0, 6-4. The unseeded Russian is making her return to Grand Slam tennis after almost a year off due to a right shoulder injury. She lost the first set of her matches in the first and third rounds, and lost the middle set in the second round.

The three-time major champion needs only a title at Roland Garros for a career Grand Slam.

No. 20 Dominika Cibulkova advanced by beating No. 29 Agnes Szavay of Hungary 6-2, 6-4 in a sloppy match that had a combined 17 winners and 66 unforced errors.

Back on the men's side, Gonzalez became the first player to reach the quarterfinals, beating Victor Hanescu of Romania 6-2, 6-4, 6-2, and Murray followed with a 7-5, 7-6 (4), 6-1 win over No. 13 Marin Cilic of Croatia.

Gonzalez, who reached the 2007 Australian Open final, ended the match with his 21st forehand winner. He finished with 50 winners and only 16 unforced errors.

"I tried to win every point," said Gonzalez, who will face Murray in the next round. "And then I'm trying to not be risky if I don't need it. Maybe I got a break, and then I can start to hit my huge shots."