A man from Brighton suffered head injuries when he was attacked in Hanover at the weekend.
He was taken to the Royal Sussex County Hospital for treatment after the attack in Southover Street at about 8.15am on Sunday (6 October).
Sussex Police said that the victim, a man in his twenties, was hit near the junction of Grove Street.
A 20-year-old local man has been arrested on suspicion of assault causing grievous bodily harm (GBH). Officers released him on police bail until Thursday 31 October while they continue their inquiries.
Detective Constable Leon Howe urged anyone who saw what happened to call Sussex Police on 101 or email contact.centre@sussex.pnn.police.uk.
Witnesses can also call the independent charity Crimestoppers anonymously on 0800 555 111.