A man has been arrested on suspicion of headbutting a driver in a suspected road rage attack in East Sussex.
Sussex Police said the 21-year-old victim was attacked at the junction of London Road and Tongdean Lane in Brighton at 0720 BST.
Officers said the victim and suspect had driven in close succession on the A23 before the attack.
The 41-year-old suspect from Bexleyheath, in south-east London, is being questioned in custody.
Police have appealed for witnesses to the incident.
Officers said a maroon Ford Escort and a black Fiat Punto were involved in the incident.