Geraint Thomas was taken to hospital after a crash during the fourth stage of the Tour of Switzerland.
Team Ineos tweeted that the Welshman, who won the 2018 Tour de France, would be undergoing medical checks.
Thomas was able to sit up and talk to team-mates before being taken away in an ambulance.
The 33-year-old has been expected to lead the team at the Tour de France since Chris Froome’s crash at the Criterium du Dauphine last week.
Thomas was involved in an accident with Astana’s Andrey Zeits on Tuesday, with both riders requiring medical attention.
The Ineos rider appeared to have cuts and abrasions to his right shoulder and back, but fears of a broken collar bone were calmed when he was seen moving both of his shoulders while being treated.
Team Ineos tweeted Thomas “was alert and speaking to the team after the crash and will be taken to hospital for checks”.
Froome is expected to be out for at least six months after suffering a fractured neck, a fractured right femur, a broken hip and fractured ribs in his crash last week.
The 34-year-old Englishman was the lead rider for Team Sky – now Team Ineos – at last year’s Tour de France before Thomas earned the support of his team as he closed in on victory in the final stages.
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Crashing comes with the territory within the pro peloton, and rarely does a rider withdraw from a race unless the injury is a serious one.
However initial reports from Switzerland suggest that he was withdrawn as a precaution, and the sight of Thomas removing his jacket whilst sat roadside hints that there’s no shoulder fracture.
With a little over a fortnight until the Grand Depart in Belgian a broken collarbone would end his chances of defending the yellow jersey he won in 2018.