A man suffered a fractured arm and facial injuries after he was stamped on during an assault in the city centre.
The 34-year-old man was attacked on Corporation Street at its junction with Halliwell Street, near to Victoria Station, at about 4.15am on New Year's Day 2013.
He was making his way up Todd Street and cut through the pedestrianised walkway towards Corporation Street to look for his brother when he was confronted by three men.
Without provocation, one of them struck him in the head knocking him to the floor. As he lay defenceless, he was kicked in the head and then as one of the men tried to stamp on his face, he put his arm up to protect himself, causing him to suffer a fracture as a result of the blow.
Eventually he managed to stagger to his feet by which point his attackers had fled.
He has described the offenders as being of mixed race and in their late teens or early 20s. One of whom was said to be wearing a yellow top.
Police are now appealing to anyone with information to come forward.
Detective Constable Paul Wilde said: "This was a particularly vicious and totally unprovoked attack on a man who, as a result, suffered a nasty fracture to him arm while trying to protect himself.
"I would appeal to anyone who either witnessed this attack, or perhaps suspects who may be responsible, to come forward immediately."
Anyone with information is asked to call police on 0161 856 3120 or the independent charity Crimestoppers, anonymously, on 0800 555 111.