A man is fighting for his life after he was knocked unconscious when he tried to intervene in a city centre brawl.
The victim, who is in his 50s, was punched in the face as around 15 people battled in Manchester in the early hours of Saturday morning.
He was taken to hospital with a serious head injury and remains in a critical condition.
A second man in his 20s was taken to hospital after suffering cuts and bruises, Greater Manchester Police said.
A 25-year-old man arrested near the scene on suspicion of affray and a 32-year-old woman arrested on suspicion of assisting an offender have been released under investigation.
Detectives are trawling CCTV footage for evidence and appealing for witnesses to the fight, outside the Printworks near Dantzic Street and Thornily Brow, to come forward.
"This was a large brawl in the city centre at a time when a lot of people would be leaving bars and clubs," said Detective Inspector Mark Davis.
"It might be that you witnessed something but didn't think to contact police at the time. If so, please get in touch with us as soon as possible.
"Just one punch on a night out has the potential to change people's lives and a man has been severely injured as a result."