Chambry - Australian Richie Porte crashed spectacularly out of the Tour de France on a treacherous and costly ninth stage on Sunday.
WATCH: Richie Porte's horrific Tour de France crash
Briton Geraint Thomas, who started the day second overall, had already crashed out 100km from the finish when Porte, who was fifth, slipped off the tarmac and onto a grass verge on the inside of a rapid descent.
He careered across the rode and clattered into Ireland's Dan Martin, bringing the two crashing into the rocky side of the road in the final 25km of the 181.5km stage from Nantua to Chambery.
"Devastating images of @richie_porte coming from the road after a nasty crash. Richie will be taken to hospital for examination," said Porte's BMC team on Twitter.
Porte was given immediate medical assistance by an ambulance and some minutes later hadn't moved.
However, organisers said he was conscious and speaking but was being taken to hospital.
Thomas had crashed on another descent much earlier in the stage and quit the Tour with a suspected fractured collarbone.
It meant race leader and reigning champion Chris Froome lost both a key team-mate in Thomas and chief rival in Porte on the same stage.
"Horrible scenes on the descent as Porte and Martin crash hard. We hope both guys are both okay," said Froome's Sky team on Twitter.
Several other riders had also quit after crashes while two-time former winner Alberto Contador was able to carry on quickly after coming down on an uphill section.
Martin continued after Porte took him down, despite crashing a second time shortly afterwards.