Kyle Thomas woke up in hospital after being hit by Dominique Eleftheriades in a smoking area outside the Barley pub in Newport's town centre on May 26 last year. He still has no memory of the night it happened beyond parking his car in Newport.
Eleftheriades, 22, has claimed Mr Thomas singled him out for his Liverpudlian accent on the night of the Champions League final between Liverpool FC and Real Madrid.
He later told police he was about to be attacked by Mr Thomas, and pushed him backwards with an open palm in self-defence.
He told officers: "I've done nothing wrong, he was about to glass me."
This week at Shrewsbury Crown Court he stands accused of causing Mr Thomas grievous bodily harm.
Jason Aris, prosecuting, told the trial that Mr Thomas was knocked backwards and fell onto his unprotected head at about 10pm.
It caused a bleed into the fluid around his brain and bruising to his brain tissue, the court heard.
Mr Aris told the court that Eleftheriades claimed Mr Thomas approached him outside the pub and asked him if he was from Liverpool before calling him a "Scouse tw*t".
Mr Thomas gave evidence to Eleftheriades' trial, saying the last thing he remembered from the night in question was parking his car at the nearby car park off Stafford Street.
Under questioning by Mr Aris, he said he wasn't sure what day it was when he woke up at the Princess Royal Hospital in Telford with his father at his side.
He gave evidence for less than 10 minutes because of his lack of recollection from the night, and he told Eleftheriades' representative Brendan Reedy that he was always in control of his actions while drinking.
Sarah Lynch who was out with friends witnessed the blow, and gave evidence to the trial by video-link from Northern Ireland.
She said: "They were quite close to each other, it looked like they were arguing. They were about two metres away, I didn't know what they were arguing about.
"It all happened very quickly. The man facing away from me had a strong Scouse, Liverpool accent.
"The gentleman with the Liverpool accent turned away very briefly and then swung back around and punched the other gentleman in the face."
She said Mr Thomas was hit with 'full body force' and his body seemed to go limp before his head hit the floor.
She continued: "I swore at him and asked what he was doing. He turned around and asked me what I was going to do about it."
A number of other witnesses called 999 while she went to Mr Thomas and put him in the recovery position. She told the court there was blood coming from his ears and nostrils.
Eleftheriades, of Forge Way in Chester, denies causing grievous bodily harm and the trial continues.