Sagan converged with the Dimension Data rider in the final metres of the sprint finish in Vittel, then his elbow flicked upwards, blocking Cavendish’s path.
Squeezed out and with nowhere to go, Cavendish fell spinning into the tarmac, his body curling as he slammed into the road at 60kmh.
Cavendish could not stop German rival John Degenkolb from riding over him, nor could Yorkshire all-rounder Ben Swift then avoid somersaulting into Cavendish’s front wheel and also falling at speed. Sagan, who dodged past the spectacular pile-up, finished second behind winner Arnaud Demare.
After reviewing video footage, UCI commissaires - responsible for race discipline - initially relegated Sagan to 115th place on the stage and docked him 80 points.
But two hours after the finish, head commissaire Philippe Marien strode into the Tour’s press room, followed by a sea of reporters and tv cameras to announce that Sagan was out of the race completely.
Sagan is the first sprinter to be expelled from the Tour in a final kilometre incident since Cavendish’s team-mate Mark Renshaw was excluded for repeatedly headbutting a rival in 2010. Prior to that, Tom Steels, a Belgian sprinter was removed after throwing a bottle at another sprinter in 1996.
This time round, Cavendish, though, came off the worst, staying slumped on the ground as medics rushed down from the finish line. Riders already entangled from a previous pile-up that had happened seconds earlier, including Tour leader Geraint Thomas - who grazed his left knee but was otherwise fine - pedalled slowly past the Dimension Data rider.
Whilst Swift was fortunately only lightly injured, Cavendish finally stood up himself, remounted his bike and was pushed by team-mate Steve Cummings across the finish line. Blood was pouring from a hand injury and cuts and bruises visible on his right leg, with his jersey ripped open from neck to waist.
Arguably the sprinter's greatest concern, though was, the state of his right shoulder, already badly hurt in a first stage crash in the 2014 Tour at Harrogate that forced him to abandon the race.
“Injury-wise I'm going to go and get it checked out,“ Cavendish, with his arm in a sling, said afterwards before he was driven away an ambulance.
“I will definitely need stitches in this finger, it's bleeding a lot. With the shoulder, it might be something to do with a previous injury, it's sat backwards so i'm not sure if I've done something to the ligament.”
“I'm not a doctor but from the feelings I’ve got, I'm not optimistic.“ After undergoing a hospital scan, it was later confirmed that Cavendish would be unable to compete in the rest of the Tour having suffered a broken shoulder.
Cavendish’s Tour had already been blighted by glandular fever earlier in the season, which wrecked his build-up for the race. The Briton’s Dimension Data team only made a last-minute decision for Cavendish to start the Tour.
After the sprint, Sagan had come to the Dimension Data bus, to apologise to Cavendish personally, but there were already calls for him to be expelled from the race.
“Time to step up #UCI. This was not a race accident. Violence. Hard to DQ a world champion from #letour, but needs to be done,” tweeted Cavendish’s team manager, Rolf Aldag. A few hours later, the UCI opted to take the drastic step of removing Sagan, an eight times stage winner, the most recent only 24 hours prior to his expulsion.
Wednesday’s stage will see a very different kind of finale as the Tour tackles its first major summit finish at La Planche des Belles Filles, with Thomas set to defend his overall lead on the same ascent where Chris Froome won in 2012.
“If it’s all together at the finish, then Froomey’s our main goal and I’ll do all I can to help him,” Thomas said. “If he gets the yellow, then great, and if I get to keep it, then even better.”
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