Tadej Pogacar will have surgery after suffering a fractured collarbone in the crash that forced him to abandon the Vuelta a España, his UAE team said on Saturday.
The five-time Tour de France champion hit the tarmac with 31km remaining in the eighth stage, ending his bid to complete a career clean sweep of the three Grand Tours.
Pogacar had been leading by a massive three minutes and 50 seconds a week into the race and was the overwhelming favourite for victory.
Spaniard Enric Mas inherited the overall leader's red jersey, 71 seconds clear of Felix Gall of Austria.
"He is stable, and following a thorough medical assessment at hospital, Tadej has been diagnosed with a concussion, a displaced left clavicle fracture, a stable C7 cervical fracture, and multiple abrasions," UAE's team medical director Adrian Rotunno said in a statement.
"Fortunately, no other major injuries and no neurological fallout.
"He will require clavicle surgery, which will be delayed due to concussion precautions.
"Tadej remains under the care of our medical team and we'll provide further updates following the surgery."