Paris ? For 31 matches, Rafael Nadal ruled the red clay of Roland Garros, boasting an unbeaten record and an unbreakable will.

For 31 matches, this was his surface, his tournament, his time.

For 31 matches, dating to his debut on May 23, 2005, Nadal never truly was challenged, much less defeated, at the French Open, allowing him to win four consecutive titles and close in on becoming the first player in history with five in a row.

Until Sunday. Until the fourth round of the 2009 French Open. Until Robin Soderling, a 24-year-old from Sweden with a bit of an attitude and 6-foot-3 worth of power, transformed Nadal’s career mark at Roland Garros from a best-ever 31-0 to 31-1 with 31/2 hours of assertive, and sometimes spectacular, play.

“Well, that’s the end of the road, and I have to accept it,” Nadal said. “I have to accept my defeat as I accepted my victories: with calm.”

Simply put, Soderling’s 6-2, 6-7 (2), 6-4, 7-6 (2) victory over the No. 1-seeded Nadal rates as one of the biggest upsets in tennis history. Not sure? Set aside all of Nadal’s bona fides for a moment — the dominance on clay; the six Grand Slam titles, including at Wimbledon and Australian Open — and focus on this: The 23rd-seeded Soderling never had won so much as a third-round match at any major tournament before this one.

“I kept telling myself, ‘This is just another match,”‘ Soderling said.

Nadal won all three of their previous meetings, including a contentious match at Wimbledon in 2007, and a 6-1, 6-0 rout on clay at Rome in April. But this time, Nadal was a half-step slower than usual — he tumbled to the ground in the third set, smearing clay all over his pink shirt and charcoal shorts — and Soderling was lights-out good.

Soderling finished with 61 winners, 28 more than Nadal, and won the point on 27 of 35 trips to the net.

The biggest beneficiary might be Roger Federer, the 13-time major champion whose resume is missing only a French Open title. Looked at another way, the pressure on Federer finally to win the championship at Roland Garros ratchets far higher. Federer lost to Nadal in each of the past three finals at Roland Garros, and in the 2005 semifinals, too.