A Secret Harbour man who punched former footballer Luke Adams told police it was a "stupid decision" to try to stop a fight between his friend and Mr Adams and he regretted his actions.
In a police 90-minute police interview less than 24 hours after the alleged assault, Dylan Winter told detectives he did not want to fight but intended to back up his friend Jake Ward.
Mr Winter, 18 at the time of the Northbridge incident early on May 1 last year, is standing trial in the District Court after pleading not guilty to unlawfully causing grievous bodily harm to the former Swan Districts ruckman. He claims he punched Mr Adams in self defence.
Mr Winter, who was arrested by police at his home on the night of May 1, told city detectives some of his friends had been kicked out of The Library and got involved in a fight with bouncers, which resulted in police issuing the group with move-on notices.
He could not remember his exact involvement in the confrontation with the club's bouncers.
Mr Winter, who told police he was "tipsy" drunk after having about 10 Canadian Club cans and two Red Bull and vodkas during the night, said the group was initially angry about the fracas outside The Library but had cooled off when they started walking down Lake Street looking for a taxi.
He said Mr Ward and his girlfriend Kara Hagen were walking behind the rest of the group when he heard Mr Ward in an argument with two men across the street, but could not hear what was being said. He said the incident happened very quickly.
"I saw these two guys having a go at him (Mr Ward), I went over and said 'back off, leave it alone', but he (Mr Adams) got in my face and said 'I'm gonna smash you' so I took a swing," he said.
The 20-year-old accused said the only reason he stepped in was because it was two against one.
But he admitted that no punches had been thrown by anyone before he intervened and in hindsight the better option would have been to grab Mr Ward and walk away.
Mr Winter said he did not think his punch was hard enough to knock the taller man out. "I didn't think I was going to be able to do what I did, he was bigger than me," he said.
"I didn't think I'd knock him out, I just didn't want him to hit me first ... I didn't think I hit him that hard."
Mr Winter, who had started training in the martial art of Muay Thai two months prior, rated the force of the punch a three out of five.
He said the taller man he punched appeared to be just as drunk as him and he rated his level of intoxication at the time a six or seven out of 10.
Mr Winter said he jogged away from the scene because he was scared of being arrested by police after being issued with a move-on notice shortly before the incident.
Mr Winter said it appeared "those guys wanted to fight Jake" and he thought there would be a fight because his friend and Mr Adams, who he did not know at the time, were approaching each other.
He accepted it was likely no one was in danger when he intervened, but he felt threatened by Mr Adams' remark when the pair faced off.
"I didn't want this to happen ... I just wanted him to stop fighting my mate," he said.
"I'd never ever done anything like this before ... this guy's bigger than me, what else am I meant to do?"
Mr Winter said that when he fled, Mr Adams was "out cold" but he thought he would wake up and get up. He said he should have stopped and helped the man he hit.
When detectives put it to Mr Winter there was no need for him to jump in between his friend and Mr Adams' verbal altercation he said: "I know that now ... I know what I did was wrong."
He said he could not remember if there was a sound as Mr Adams' head hit the ground.
Mr Adams suffered a fractured skull and life-threatening brain injuries and other witnesses have described hearing a loud "crack" as he fell.
Mr Winter said that later that night he tried to "suss out" with his friends if the man he punched was OK, but no one knew.
The jury was told Mr Winter has no criminal history.
Mr Ward's girlfriend, Kara Hagen, gave evidence yesterday that Mr Winter was either pushed or hit to the ground by the tall man he was fighting with before he got up and punched the man.
In his police interview, Mr Winter made no mention of being on the ground.
Prosecutors closed their case today after showing the jury a video of the Lake St scene taken several hours after the incident which showed blood stains on the pavement where Mr Adams hit his head.
Mr Winter will reveal tomorrow whether he will take the stand and give evidence in his own defence.
The trial continues.