Mark Cavendish has abandoned the Abu Dhabi Tour after crashing in the neutral zone on stage one.
The Manx rider, who won the opening stage of last year's race, hit the deck shortly after setting off from Madinat Zayed.
The 32-year-old got back on his bike but was forced to abandon soon after with his team revealing he suffered whiplash and a concussion in the crash.
"Mark sustained a concussion and a whiplash injury after his crash today," Dimension Data doctor Adrian Rotunno said on the team's website.
"Due to the concussion, we were not willing to risk rider safety and the call was made for Mark to stop the race.
"A serious neck injury has been excluded in hospital. He currently has some concussive symptoms and neck pain, but is otherwise stable. We will monitor Mark's condition closely going forward."
Cavendish had earned his first victory of 2018 by winning the third stage of the Dubai Tour in a sprint finish earlier this month.
That meant he continued his run of winning at least one professional race in each of the last 13 seasons.