The victim - Paul Ologbose, 57, - is thought to have been hit once to the head at Higher Folds Sports and Social Club on Kensington Drive, Leigh, shortly before 1.55am on Sunday, January 23.
He was taken to hospital with a critical head injury and, sadly, lost his battle for life several hours later.
A man in his 40s was arrested on suspicion of assault soon after the incident and, following Mr Ologbose's death, was re-arrested for murder.
Well known in the Leigh area by the nickname Bushy, Mr Ologbose has been the subject of warm tributes on social media since details of the tragic incident emerged.
Amanda Haigh wrote: "Heartbreaking, absolutely fantastic guy. You will be sadly missed by all those who had the pleasure of knowing you. Thoughts are with Paul's family."
Kaysha Jones wrote: "RIP Bushy: one of the best neighbours ever and such a kind man who had a heart of gold would help anyone out in need. Thinking of all the family at this sad time."
Katie-Louise Power said: "So sad thoughts are with hid family at this awful time. When will people realise it only takes one punch to end a life? There is no excuse for violence, grown men what an example to set to young people."
Wendy Bridges wrote: "A terribly sad incident. One punch. It’s just not worth it. Lots of lives ruined for two families, very sad."
Sade Claire McDonald said: "This is awful! Know Paul from coming in my place of work and he was such a gentleman, always happy and made time to have a chat. Thinking of his family and friends."
And there were more than 200 more messages in a similar vein paying tribute to a polite and friendly man.
Detectives are pursuing several lines of investigation - including speaking to those at the social club, which is on Kensington Drive, and reviewing any CCTV in the surrounding area.
Anyone with information about the attack is urged to contact police as any detail could prove vital.
Det Supt Rebecca Boyce, of GMP's Wigan district, said: "A man has horrendously lost his life after suffering a serious head injury that we believe was sustained from one punch during an altercation on a night out.
"It's a shocking and distressing time for Paul's family and we will do what we can to support them through our ongoing investigation.
"We have a suspect in custody who is being interviewed in relation to Paul's death, but it's vital we capture the full circumstances of this awful incident, and I therefore implore anyone with information to do the right thing and get in touch."
Details can be passed to police by calling 101 quoting incident 302 of 23/01/2022.
Information can be passed anonymously to the independent charity Crimestoppers on 0800 555 111
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