A man suffered serious head injuries in an attack at a nightclub.
It happened at about 04:00 BST at the Bijou Club, in Chapel Street, Manchester, which bills itself as a "celebrity hangout".
Police said the victim, 31, was in a serious but stable condition.
"This was a particularly nasty assault, during which this victim sustained serious head injuries which at first were thought to be life-threatening," said Det Ch Insp Elizabeth Hopkinson.
"Fortunately that is no longer the case, but that should take nothing away from the severity of this attack."
Police are appealing for anyone who may have seen what happened to come forward.
The Bijou Club opened in 2009 and said celebrity guests had included Justin Bieber, Ne-Yo, Tulisa, Drake, Rita Ora, Little Mix and The Wanted.
The club has not been available to comment.
Update 21 April 2017: Initial information from the police suggested an axe had been used in the attack but it transpired this had not been the case and our story has been amended.