Late night violence broke out in Watford town centre after a party of six men were ejected from the Walkabout bar, a jury heard.
The group, who were from the Tudor Arms Football Club in Bushey Mill Lane, had been identified wrongly as being involved in trouble inside the bar, St Albans crown court was told.
While door staff went back inside to find the men involved, a fight broke out involving the Tudor Arms group and two music promoters who had been ejected just before them, it was alleged.
Walkabout's Head Door Supervisor Michael Collins told the jury that he and a colleague were on duty at the entrance to the bar when they got a call to go inside as a "fight was kicking off".
He went on: "Two black guys were having aggro. We took them outside. They said they weren't the ones fighting. We went back in and talked to bar staff and picked out a group of guys - all white and well dressed. They were wearing white shirts and red ties. We took them out."
But he said the two men they ejected first said they were not the men who had been causing the trouble. Mr Collins and his colleague went back inside, but could not find the men. When they went back outside he said a fight had broken out. He said a light skinned black man was curled up in a foetal position being kicked.
He ran over and pulled people out of the way before a punch missed him by a millimetre and connected with one of the group who "fell like a sack of potatoes".
Mr Collins said he cradled the man who had been knocked out cold for 20 seconds. A girl was screaming and he said at first he thought the man had cracked his skull on the cobbles as he saw blood flowing. He then realised he was bleeding from his mouth. He said an ambulance arrived, but the man did not want to be treated. When the police got there he said the group scattered.
Prosecutor Sonya Saul said the trouble started at around a quarter to midnight. She played CCTV footage to the jury of seven men and five women, which showed fighting in the street outside the club involving a large number of people.
Ben Collins, 26, of Mundesley Close, Watford; Jack Hawton-Hill, 20, of Radlett Road, Watford; Calum O'Connor, 24, of Tudor Avenue, Watford; and Luke Pocetty, 26, of Meadow Road, Watford, all deny affray on April 21, 2013.
When he was arrested on July 3 last year O'Connor told the police he could not remember a lot as he was knocked out. He said he had played for the Tudor Arms that day and was happy on the night out. He said he had six or seven beers that night, but was not drunk. He told the officer he was in the "wrong place at the wrong time".
Luke Pocetty made no comment. Ben Collins said he had also played for the Tudor Arms and had drunk four or five pints. Jack Hawton-Hill said he was acting in self defence and threw punches to protect himself.