Colombian cyclist Egan Bernal suffered an accident while training in his country, his team Ineos said.
The runner was taken to the hospital where he is "under observation" and "conscious".
The images shared on social media show the 25-year-old, last year's winner of the Giro d'Italia, lying on the ground surrounded by teammates.
"Bernal was accompanied to the hospital by the Team's medical staff and was conscious upon arrival. He is stable and is undergoing further evaluation."