Police have decided there are no suspicious circumstances after a 21-year-old man was found in the town centre with serious head injuries.
The man, who is from Essex, was discovered in Glen Fern Road at 4.30am on Saturday morning.
The force confirmed on Monday afternoon that they believed the man had been involved in an accident.
The man remains in a stable condition at Southampton General Hospital.
A large cordon was extended into St Peter's Road and Glen Fern Road on Saturday morning to allow forensic officers to examine the scene.