A teenager from Littlehampton has broken his wrist after a silver car pulled out in front of his motorbike in Worthing, police said.
Sussex Police are looking for witnesses to the incident, which happened on Tuesday afternoon in Worthing.
A police spokesman said: "A silver car pulled out of the junction of Dominion Road and Angola Road at 4.20pm, apparently causing the rider to take avoiding action, but the two vehicles were not in collision.
"The motorcyclist, an 18-year-old man from Littlehampton, initially said that he was uninjured and the driver of the car did not exchange details.
"Anyone who witnessed the incident or indeed, the driver of the silver car, is asked to report online at https://sussex.police.uk/appealresponse or call 101 quoting serial 946 of 25/09."