CCTV cameras recorded Jason Emmerson struggling with the man outside a pub on Victoria Square, just before midnight on October 30 last year, said prosecutor Alexis Mercer.
Door staff and other members of the public tried to convince him to “leave it,” but Emmerson continued shouting and squaring up to him.
He threw one punch, but it was unclear if it connected, and then another which made him fall over.
As more people became involved, Emmerson's victim walked away, but Emmerson followed him and hit him in the face, knocking him unconscious.
Ms Mercer said the incident wasn't charged as an assault, because the victim didn't want to provide an account to the police.
“Many people went to great lengths to persuade him to walk away,” said Ms Mercer. “There is a level of provocation from the victim.”
The court heard Emmerson, aged 25, has six previous convictions, including common assault, in 2018. He recently completed an 18 month community order, imposed at Nottingham Crown Court, in 2020, for affray.
Morgan Hogarth, mitigating, said the defendant was “dealing with the fact his grandfather was being treated for terminal cancer at the time.”
He said Emmerson went out for a drink and, minutes before the incident, CCTV showed him “chatting amiably to the door staff outside the pub and a couple of other customers as they come and go.”
But when group of three men were turned away from the pub and became verbally abusive, Emmerson reacted, and claimed he was punched in the jaw during the initial struggle.
“More people who know Mr Emmerson from around town tried to pull him away for his own good,” Mr Hogarth said.
Mr Hogarth said Emmerson, a forklift driver, has asked to be barred from Worksop town centre pubs “because he doesn't want to be drinking in his current state of mind.”
Emmerson, who gave his address as Winthorpe Street, Mansfield, admitted using threats and behaviour to provoke unlawful violence, when he appeared at Mansfield Magistrates Court, on Thursday.
The case was adjourned until January 27, for a pre-sentence report to be prepared.