A spokesperson for Belgian Cycling, Gwendoline Gerres, said the collision caused a severe impact to his upper body. Because of the injury, Seff cannot race in the junior individual time trial on Tuesday or the road race on Thursday at the UCI Road World Championships.

This is Seff’s second car collision in nine months. A crash in Belgium in December broke four of his vertebrae, and he only returned to training in April.

His brother Matisse said a car suddenly drove across the street, probably to turn onto a driveway. The driver did not see Seff, and because Seff was on time‑trial handlebars he could not brake in time.

The Belgian cycling federation said it will not replace Van Kerckhove in either of the races he was scheduled for.