A man who asked three men to stop throwing litter was subjected to a "mindless" unprovoked attack which left him in hospital, police said today.
The attack happened at around 3.45am on Saturday as the 23-year-old victim was making his way home from a night out with his girlfriend in Manchester.
He was walking along Piccadilly towards the station and was passing the Abode Hotel when he saw three other men kicking bins and throwing rubbish around.
He confronted the trio, who turned on him, punching him to the ground and then kicking him in the head and body while he lay defenceless, police said.
The men then ran off towards Dale Street and Tariff Street.
The victim was taken to hospital where he had to undergo X-rays and scans.
Police are appealing to anyone who either witnessed the attack or who has information about what happened to come forward.
Detective Constable Paul Shacklady said: "This man was simply trying to do the right thing when he confronted a group who were acting in a very anti-social manner.
"He was then subjected to a totally unprovoked and mindless attack by this trio, and frankly the injuries could have been a lot worse.
"We have all seen how serious the consequences can be of such violence and it is very important we track those responsible down and bring them to justice."
He added: "I want to particularly appeal to the consciences of either family or friends of the offenders.
"Please, the victim was extremely lucky to escape without more serious injuries and it could have been far worse. If you do know what happened, do the right thing and call us."
The men were all white and in their early 20s.
The first man has brown hair and was wearing skinny jeans, possibly three-quarter-length, a red checked shirt, dark-coloured T-shirt and light-coloured trainers. He had tattoos around his neck, one of which may have been a face, and he also had piercings.
The second man was wearing a blue denim shirt, a white T-shirt and dark skinny jeans. The third was wearing skinny jeans.
Anyone with information is asked to call police on 0161 856 3554 or Crimestoppers, anonymously, on 0800 555 111.