Eastern District Detectives are investigating an assault which has left a man in hospital with a head injury.
At 1.15am, Sunday 15 December, police and paramedics were called to King William Street near Gilbert Place after reports of an assault.
The victim was punched following an altercation on a bus a short time prior. The man then walked off and was last seen walking north on King William Street.
The victim was taken to the Royal Adelaide Hospital where he remains in a serious condition.
Police are appealing for anyone who may have witnessed the incident or have any information to contact Crime Stoppers on 1800 333 000 or report online at www.crimestopperssa.com.au