Richie Porte crashed out of the Tour de France before John Degenkolb won a chaotic stage nine over the cobbles to Roubaix yesterday.
BMC's Porte, among the favourites for overall victory, crashed long before the first cobbled sector, just seven kilometres from the start in 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 in an action-packed stage, while Romain Bardet suffered a string of mechanical issues as the general classification was given a proper shake by the cobbles.
Greg Van Avermaet stayed in yellow, extending his lead over Team Sky's Geraint Thomas to 42 seconds by finishing second, but there were losses for Landa, Bardet, Uran and others while Froome and Mitchelton-Scott's Adam Yates moved into the top 10, both now one minute 42 seconds down.
Ireland's Dan Martin, who emerged without any fractures in a high-speed crash on Saturday's stage to Amiens, finished among the main group yesterday in 32nd place.
Since the 2018 Tour route was announced in October, this day had been circled as the wildcard and it did not disappoint. The cobbles made up only 21.7km of the day's route, but brought with them a constant battle of nerves, such is the likelihood of crashes and mechanical problems.
Porte did not make it far enough to see them, caught in a huge tumble early on as he crashed out on stage nine of the Tour for a second straight year.
Froome recovered from his own tumble on the eighth cobbled sector to finish in a much-reduced peloton alongside Sky team-mate Thomas, but others were not so lucky.
AG2R La Mondiale's Bardet suffered a remarkable five separate mechanical problems, the last of them as he exited the final cobbled sector only six kilometres from home, but was able to limit his losses against the rest of the contenders to just seven seconds.