A 50-year-old man suffered a serious head injury when he was knocked to the ground outside a bar, police have said.
The assault happened during a disturbance outside the Buf in Prestwick, South Ayrshire, at around 2.15am on Sunday.
Police said the victim was walking past the Main Street venue when he was assaulted and fell back onto the pavement.
He is said to be in a serious condition at Ayr Hospital.
Detective Sergeant Barry Walker said: “A man is lying seriously injured in hospital and it is absolutely vital that we trace the individual responsible.
“Main Street would have been busy at the time of the incident and I would appeal to anyone who witnessed a disturbance, or anything at all which could be of significance, to please get in touch.”