Richie Porte crashed out of the Tour de France as John Degenkolb won a chaotic stage nine over the cobbles to Roubaix, with Ireland's Dan Martin finishing in 32nd place.

BMC's Porte, among the favourites for overall victory, crashed long before the first cobbled sector, just seven kilometres into the 156.5km stage from Arras.

The 33-year-old Australian appeared to be holding his collarbone before being taken away for X-rays.

He was not alone in suffering as Chris Froome, Mikel Landa and Rigoberto Uran also hit the deck, while Romain Bardet suffered a string of mechanical issues as the general classification was given a proper shake by the cobbles.