Vincenzo Nibali extended his lead but defending champion Chris Froome is out of the Tour de France after crashing twice during stage five.
Froome crashed at the beginning of stage four and was heavily bandaged up going into stage five, but with weather conditions being extremely wet and slippery the Team Sky rider crashed after just 30km before going down again with around 69km to go.
It was clear after the second fall the Froome was in a lot of discomfort but it initially looked like he was going to get back on his bike, however after a few moments and a shake of his head he got in the team car and was driven to the finish.
The riders had already said they weren't looking forward to stage five, as it had 13km of cobbled sections, which in rain are extremely dangerous. Froome didn't even make it to the first of these cobbled sections before retiring from the race.
New lead rider
Team Sky will now turn to Richie Porte, and they will hope he can battle for the yellow jersey. Geraint Thomas will have to support him as the new team leader.
Lars Boom claimed the stage victory after breaking away from Vincenzo Nibali and Jakob Fuglsang in the final six kilometres. Fuglsang finished second with his team leader Nibali crossing the line right behind him in third.
Nibali's overall lead has now grown considerably after Froome retired and Alberto Contador struggled on the wet cobbles. Contador is now two minutes 55 seconds behind the yellow jersey, sitting 19th in the general classification.
The Italian said: “It’s been an unbelievable day out there today. I took quite a lot of risks and there were at least three occasions when I very nearly fell off my bike.
“But thanks to luck and some experience as well, being able to ride safe for the majority of it, taking the right corners, it has gone very well in the end."
Stage five result
1 Lars Boom (Ned) Belkin, 3:18:35
2 Jakob Fuglsang (Den) Astana, +0:19
3 Vincenzo Nibali (Ita) Astana, st
4 Peter Sagan (Svk) Cannondale, +1:01
5 Fabian Cancellara (Swi) Trek Factory Racing, st
6 Jens Keukeleire (Bel) Orica-GreenEdge, st
7 Michal Kwiatowski (Pol) Omega Pharma - Quick-Step, +1:07
8 Lieuwe Westra (Ned) Astana, +1:09
9 Matteo Trentin (Ita) Omega Pharma - Quick-Step, +1:21
10 Cyril Lemoine (Fra) Cofidis, +1:45
1 Vincenzo Niabli (Ita) Astana, 20:26:46
2 Jakob Fuglsang (Den) Astana, +0:02
3 Peter Sagan (Svk) Cannondale, +0:44
4 Michal Kwiatkowski (Pol) Omega Pharma - Quick-Step, +0:50
5 Fabian Cancellara (Swi) Trek Factory Racing, +1:17
6 Jurgen Van Den Broeck (Bel) Lotto-Belisol, +1:45
7 Tony Gallopin (Fra) Lotto-Belisol, st
8 Richie Porte (Aus) Team Sky, +1:54
9 Andrew Talansky (USA) Garmin-Sharp, +2:05
10 Alejandro Valverde (Spa) Movistar, +2:11
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