Gino Mader has been airlifted to hospital after crashing heavily on stage five of the Tour de Suisse.
The Team Bahrain Victorious rider and American Magnus Sheffield, 21, were attended to shortly after crashing on the descent of the Albula Pass.
Sheffield, of Ineos Grenadiers, was responsive but Swiss Mader, 26, “lay motionless in the water”.
“He was immediately resuscitated and then transported to Chur hospital by air ambulance,” a Tour statement said.
It added that the severity of Mader’s injuries and the circumstances of the accident “are being clarified”.
Sheffield was taken to Samedan hospital with bruises and a concussion.
Ineos Grenadiers later said Sheffield also sustained soft tissue damage and “will be kept in hospital overnight for observation, continued care and monitoring”.
Organisers said the race doctor was on the scene of the accident within two minutes.
