American Chloé Dygert crashed over a guard rail and failed to finish the world road cycling championships time trial, where she appeared en route to a repeat title in Imola, Italy.
Dygert, who last year won by the largest margin in history as the youngest-ever champion, lost control of her bike while approaching a curve to the right. Her front wheel bobbled, and she collided with the barricade, flipping over into an area with grass.
Her condition was not known when, about 10 minutes later, Dutchwoman Anna van der Breggen won her first time trial title.