Briton Mark Cavendish abandoned the Abu Dhabi Tour after sustaining a possible shoulder injury in a crash, his team said on Wednesday.
"He went down in the neutral zone, falling on the same shoulder he broke last year," Team Dimension Data said.
"He got up and chased back to the peloton but had to abandon soon after."
Cavendish suffered a right shoulder blade fracture at the end of the fourth stage of last year's Tour de France.
Cavendish is an ambassador for the Abu Dhabi Tour and has won three stages of the race over two years. In 2017, he won the green jersey for general classification points. Cavendish was ruled out of the inaugural race in 2015 due to a shoulder injury.
As one of the world's leading sprinters, Cavendish would have been a strong contender in the first three stages, which are all designed to cater to a bunch sprint finish.