Professional footballer Rohan Ince attacked a bouncer with a Jack Daniels bottle - jumping up and hitting him with it in a "slam dunk", a court heard.
The 24-year-old Brighton & Hove Albion midfielder denies wounding with intent outside Atik nightclub in Windsor in the early hours of Christmas Day in 2015.
Reading Crown Court heard doorman Gregor Jurcic, 27, suffered a "nasty" head injury that required seven staples and has been left with scarring.
A jury heard Ince denies being the person that attacked Mr Jurcic, who was helping police disperse revellers at the time, with the bottle.
Up to 500 people had gathered outside the nightclub, on Victoria Street, between 3.30am and 4am on that Christmas morning.
Prosecuting, Nigel Daly said: "There was trouble brewing. The police were in attendance but they were grossly outnumbered."
Security staff from the nightclub, including Mr Jurcic, were helping officers control the crowds.
Mr Jurcic was attacked with a bottle from behind as he went to help a police officer restrain an aggressive man.
Michael Zgorzalek, another member of the security team, saw a black man run towards Mr Jurcic and attack him.
"He saw this man jump up into the air and bring the bottle down on to his head. Having done that, Mr Ince began to run from the scene," Mr Daly said.
"A police officer took him to the floor. As he did so, the bottle came out of his hand and span across the road."
Ince was arrested and taken to Maidenhead Police station, while Mr Jurcic was driven to Wexham Park Hospital by ambulance.
The doorman had sustained a cut measuring between 5-7cm on his head, which required seven metal staples.
In a police interview, Ince claimed he had punched a man who had attacked his brother. He insisted he had not been holding a bottle.
Ince, of Ashford, Middlesex, said he tripped while running away and was then "mounted" by a police officer and a doorman.
Mr Jurcic's blood was found on Ince's jacket and CCTV footage shows a bottle coming away from the footballer as he is tackled to the ground, the jury heard.
Giving evidence, Mr Jurcic said he had not seen the person who hit him, as he was attacked from behind.
"I felt a thud, a sharp object hit me from the side," he said. "There was the sound of it and there was glass on me."
Mr Zgorzalek told the court he could see Mr Jurcic splitting up a group of men who were on the street outside the club.
"I could see a guy who was running with a bottle in his hand," he said. "I could see him jumping up and doing an NBA-style slam dunk with the bottle. It was a Jack Daniels bottle.
"The thing I found quite shocking was the JD bottle was smaller than the normal one litre. That smashed on his head.
"The smaller bottle is a lot, lot stronger so he must have whacked him with some force to smash that bottle."
Mr Zgorzalek said he helped a police officer restrain Ince, who apologised before asking "are you sure it's me?".
Ince denies a single charge of wounding with intent, which alleges that he unlawfully and maliciously wounded Gregor Jurcic with intent to cause him grievous bodily harm.
The trial continues.