Police have released CCTV images of a man they want to trace over an attack in Edinburgh on New Year's Day.
A 29-year-old man was hit in the face on South Bridge at about 05:15 on 1 January.
He was seriously injured and needed hospital treatment.
Police believe the man in the images may be able to help with their investigation, and they urged anyone who recognised him to contact them. He is mixed-race, with short black hair.
He is aged 18 to 21, about 5ft 7in and of slim build.
He was wearing a black hooded jacket, black trousers, a red item near his waistband and dark trousers with a white rim.
Det Con Darren McDonald, of Police Scotland, said: "The victim sustained a painful injury following an unprovoked attack, and we believe the man pictured may have information which could be of assistance to our investigation.
"We're now appealing for the public's help as part of our inquiries and would urge anyone who recognises him, or who may have been in the area at this time and has information of any relevance, to come forward."