It happened on Albert Street just before 2am on Sunday.
Police are appealing for witnesses following a serious assault in Bury.
Shortly before 2am on Sunday 21 April 2019, three men were walking along Albert Street, when they were approached by two men.
After a short verbal exchange, one of the two men punched one of the group of three men to the face, causing him to fall and hit his head.
The victim, a man in his 20s, was taken to hospital where he remains in a serious but stable condition with injuries that are not believed to be life threatening.
The offender and his accomplice left the scene after the attack.
The offender is described as black, with a shaved head and medium build.
His accomplice is described as Asian.
No further descriptions are currently available.
Detective Superintendent Howard Millington of GMP’s Bury District said: “This was a nasty, unprovoked assault on a young man who was simply out with friends enjoying himself.
“We’re pleased that he’s recovering well, but his injuries could have proven far worse.
“While we have limited descriptions of the offenders at this time, we believe there may be several potential witnesses to this incident, or people who saw the offender shortly before or after the incident.
“Were you in the Albert Street area at the time? Perhaps you saw two people matching our descriptions or have some information that can help us. If so, please get in touch as soon as possible.”
Information can be left with officers on 0161 856 1063 or the independent charity, Crimestoppers, anonymously, on 0800 555 111.