Chavanel joined an early breakaway and raced home on his own
Frenchman Sylvain Chavanel took over the leader's yellow jersey after winning a dramatic second stage of the Tour de France from Brussels to Spa.
The 31-year-old was part of an eight-man breakaway after 10km and remained clear as his rivals dropped back.
The main peloton were three minutes 56 seconds back after a large number of riders went down on the wet roads.
Lance Armstrong, Alberto Contador, Andy Schleck and Bradley Wiggins all fell but were able to rejoin the pack.
Quick Step rider Chavanel seized yellow from Swiss Fabian Cancellara, who held up the field to allow the likes of Armstrong, defending champion Contador and last year's runner up Schleck to catch up following a number of spills on the slick Belgian roads.
Cancellara then orchestrated a go-slow in protest as the peloton crossed the line in union.
Chavanel leads Cancellara by two minutes 57 seconds with German Tony Martin third a further 10 seconds back.
"It's a lot of emotion and it shows how the wheel can turn in cycling," said Chavanel, who was injured on the same roads two months ago in the Liege-Bastogne-Liege classic.
This time, Chavanel was among a minority of riders who did not crash on the descent of the Stockeu, 30km from the finish, and as rival Jurgen Roelandts tired, the Frenchman went for home 19.5km out.
"I didn't know what was going on behind me, although I did hear there'd been a crash. All I know is that I gave it everything I had," he said.
It's moments like that I wonder why I came off the beach
"But whether the stage ended up being neutralised or not, it doesn't take anything away from my win."
American rider Christian Vande Velde, who broke two ribs in one of the crashes, later withdrew from the Tour after going to hospital.
Vande Velde was one of five Team Garmin-Transitions riders to be hurt, including David Millar, who suffered a potential broken rib, while Tyler Farrar fractured his left wrist, though he intends to start Tuesday's stage.
"He's got significant injuries, so starting alone is a huge step, and from there we'll have to see how he goes," said Garmin's Director Sportif Jonathan Vaughters of Farrar.
Seven-time champion Armstrong was another rider to go down in treacherous conditions and the 38-year-old said afterwards: "It's moments like that I wonder why I came off the beach, but I'll be back at it tomorrow."
Armstrong's team manager Johan Bruyneel said: "Lance is OK, he's got a wound on his hip and his elbow.
"Riding downhill was almost like ice-skating. Almost half of the peloton crashed."
Sky team principal Dave Brailsford was left to survey injuries to a third of his nine-man team, including Wiggins, who injured his leg.
"It was ridiculously slippy," said Brailsford.
"They were coming down the last couple of descents and there were guys in the trees.
"It was carnage in the true sense of the word.
"Sixty guys must have crashed in different places."
A statement from Contador's Astana team claimed a fuel spill was to blame for the slippery road: "Alberto was one of the many riders who suffered a fall on a road that had turned into a skating rink due to rain and, apparently, the loss of fuel of a motorcycle which had fallen minutes before the riders passed."
Britain's David Millar is fourth overall, 3:17 back, with Armstrong 3:19 behind in fifth and Contador 3:24 behind in seventh.
British sprinter Mark Cavendish, who crashed on Sunday, trailed home almost 10 minutes behind.
Before the end of the stage, Cancellara agreed with the race commissionaire that no points classification sprint awards would be made at the finish to avoid further incident.
"Everybody recognised what happened so I think there was a bit of common sense among the riders," added Brailsford.
"They might be competing, but I think there's a degree of solidarity too."
But Thor Hushovd, who beat Cavendish to the green jersey in 2009 by 10 points, was annoyed that the non-contested finish prevented him opening up a gap in the points race.
"I feel like they have taken something away from us today," said Hushovd.
"There was no reason to not contest the sprint today.
"I lost an important opportunity to try to win the stage and gain points."
Armstrong refused to blame Tour organisers for the chaos that ensued in the wet conditions.
"These hills around here and the Ardennes are legendary, it's part of cycling," he said.
"Liege-Bastogne-Liege has been around for a hundred years and they do that on the snow. We can't say that.
"For whatever reason the road was slippery and it's by no means any fault of the organisers. It's just bad luck."
Tuesday's stage takes the riders from Wanze to Arenberg Porte du Hainaut featuring four cobbled sections - totalling 13.2km - used in the Paris-Roubaix spring classic.
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