The victim, a 19-year-old man, was outside the Art Picture House, The Haymarket in Bury when he was punched by a man who had just left the same pub.
The punch broke the victim’s nose and caused him to fall backwards and hit his head on the pavement.
The victim suffered a fractured skull and a bleed on the brain but has now recovered from his injuries.
The offender was tracked on CCTV fleeing the scene and taking refuge in Venue bar on Silver Street.
Police have released a CCTV image from Venue of a man they want to speak to in relation to the assault.
Detective Constable Gordon Milne, of GMP’s Bury Division, said: “This was a shocking, violent attack that left a man with very serious injuries, from which he has thankfully now recovered.
“If you recognise the man in this CCTV image, we would urge you to contact police as soon as possible.”
Anyone with information should call police on 0161 8568045 or the independent charity, Crimestoppers, anonymously, on 0800 555 111.