On a day of chaos and crashes, riders tumbled like dominoes in the rain and littered the road in a scene Lance Armstrong called "surreal".

The seven-time champion did not escape the mayhem at the Tour de France on Monday. He was left searching for his bike, nursing scrapes and bruises to his hip and elbow and joking about the decision to come out of retirement.

He was in good company, joining dozens of riders who hit the asphalt on a slippery downhill run some likened to ice skating.

Sylvain Chavanel of France was among the few to avoid trouble. He sped to victory after breaking away early in the 125-mile trip from Brussels to Spa and took the yellow jersey from Switzerland's Fabian Cancellara. With the pack banged-up, he finished nearly four minutes ahead.

With so many riders down in crashes, organizers said they briefly considered canceling the stage altogether. But under the race rules, the spills were too spread out to warrant a cancellation.

Armstrong returned to the RadioShack team bus with his team outfit torn and a bloody scrape on his thigh. His team said he also injured his elbow but otherwise was all right.

"You had people everywhere. It was surreal. When I got back on my bike ... I saw crash, after crash, after crash," Armstrong said, noting riders laid out on the ground. "It was like war."

Chavanel began the stage in 87th place and knocked everyone on the leaderboard down a notch: Cancellara dropped to second, 2 minutes, 57 seconds behind. Germany's Tony Martin is third, 3:07 back.

Armstrong sits fifth, 3:19 back, and defending champion Alberto Contador of Spain is seventh, 3:24 behind. The Spanish two-time Tour winner bruised his right hip, knee and elbow but was expected to start on Tuesday.

Some riders believed a motorcycle crash in the race caravan before the pack passed left oil on the road, creating an especially slick mix with the rain.

On the descent from the midlevel Stockeu Pass, Armstrong, Contador and 2009 runnerup Andy Schleck all went down. Armstrong said he knew he was not badly hurt but he did have other concerns.

"I knew I was fine," he said. "My first thought was: 'Where is my bike?' I tried to find my bike. You know in the rain these guys are very good downhill. I'm not one of them. But even the good ones, with something like that: No chance. Absolutely no chance."

Everybody finished, except French rider Mickael Delage, who slammed into a road barrier early in the stage. The Omega Pharma-Lotto rider was taken to hospital with a concussion, a broken bone in his face and shoulder, knee and hand injuries.

Scrapes and bruises were reported by the dozens and nearly every team was affected. Some riders estimated at least half the 194-rider peloton had fallen. A post-stage medical report listed 23 as at least slightly injured during the day.

On the Garmin-Transitions team alone, Americans Tyler Farrar and Christian Vande Velde and Julian Dean of New Zealand were taken to a hospital for evaluation.

"Riding downhill was almost like ice skating," said Johan Bruyneel, the RadioShack manager and Armstrong's longtime mentor. Teammates Andreas Kloeden and Levi Leipheimer fell. "Almost half of the peloton crashed today," Bruyneel said.