Favourites Julian Alaphilippe and Michał Kwiatkowski have both abandoned the Tour of the Basque Country.
The pair were both caught in a high-speed crash in the closing 5km of stage three, but were able to get back on and finish the stage.
Alaphilippe (Deceuninck – Quick-Step) and Kwiatkowski (Team Sky) both suffered cuts and bruises and escaped serious injury, but they left the race on day four.
Winner of stage two Alaphilippe didn’t start stage four, while Kwiatkowski abandoned part way through the race.
Team Sky’s Jonathan Castroviejo came of worse in the fast collision, suffering multiple breaks and he is likely to require surgery.
The team’s doctor Iñigo Sarriegui said: “Jonathan has a fracture of his right clavicle as suspected.
“We will get a surgical opinion on that and the likelihood is he will need an operation.
“He’s got a few smaller fractures too, although it’s unlikely they will need any intervention.
“One of his ribs is fractured, he has a very small fracture on his left wrist, and he has a stable fracture of parts of his vertebrae.
“He should go home today, after staying in overnight for observation.”
Tour de France champion Geraint Thomas was also involved in the crash, but escaped injury and finished the stage.
He said: “I’m okay after the crash, especially considering the speed we were going.
“I’m obviously a bit sore but it could have been a lot worse.
“I landed on the same spot as when I fractured my pelvis during the Tour back in 2013, but it’s nowhere near as painful.
“We’re just all sending Castro our best wishes.”
Alaphilippe said after the stage that his injuries didn’t seem to be serious and that his team would monitor him overnight.
He said: “I don’t really know what happened, just that it was a touch of wheels in front of me and in the next moment I was on the ground.
“It’s the first time in my career that I’ve crashed at high speed, but at the end of the day I am happy I could finish the stage.”
The Frenchman had been second overall but lost 12 minutes after the crash and opted not to start stage four.