Reigning world champion Chloe Dygert crashed out of the UCI Road World Championships during the individual time trial on Friday, while Dutchwoman Anna van der Breggen won the race and will collect the rainbow jersey.
Dygert, 23, from the U.S., took a sweeping corner wide and, unstable on her bike, crashed into and toppled over a roadside barrier, falling down the grass bank on the other side during the 31.7km circuit at Imola, Italy.
Her Team USA car immediately came to her rescue, and the six-time Olympic medallist was treated by medical staff at the side of the road before being transferred into an ambulance. USA Cycling tweeted Dygert was conscious and talking, but did not give details on the extent of her injuries.
Her father, David Dygert, later told the Indy Star that she was airlifted to a hospital in Bologna and was undergoing surgery to repair a "severed or severely damaged" quadriceps muscle.
Dygert's father told the paper that the initial X-rays showed there were no broken bones, but his daughter's quadriceps was sliced "from one side to the other."
Dygert was on target to win her second time trial world championship.
World road race champion Van der Breggen won the individual time trial in 40 minutes, 20 seconds. She was 15 seconds ahead of Marlen Reusser of Switzerland, and 31 seconds ahead of Ellen Van Dijk from the Netherlands.
The UCI Road World Championships continue tomorrow with the elite men's individual time trial at Imola's motor racing circuit after being moved from Switzerland due to COVID-19.
The Associated Press contributed to this report.