Detective Sergeant Graeme McArthur said: “The assault took place at Little May Street in Belfast City Centre shortly after 2.30am in the early hours of Sunday 25th November.
“As well as the injured party and the assailant; a male walking alone, and a male and female couple are also believed to have walked along Little May Street in the direction of Catherine Street North at the time of the incident.
“I would ask these three individuals to give detectives at the Public Protection Unit at Strandtown Police Station a call with any information they may have.
“The number to call is 101 and the reference number is 246 25/11/18.”
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”