Mr Harborow told the court Morrison ran up to the other man and deliberately punched him in the head, causing him to fall backwards and knock his head on the sidewalk.
"This was not, the Crown says, a case of self-defence. Rather, the Crown says Mr Morrison found the broken door and pursued Mr Harris down Dominion Rd and went straight up to him and punched him. Certainly he did not intend to kill him, but those were the consequences of his actions."
Morrison's lawyer Lorraine Smith said he had been trying to talk to Mr Harris when he became aggressive and came into his space.
Morrison merely pushed him with the palm of his hand, causing him to fall over.
It was a clear case of self-defence, she said.
The court heard evidence from Michael O'Malley, who saw the incident unfold as he walked down Dominion Rd.
Mr O'Malley, who Mr Harborow described as a key Crown witness, had been at the nearby Clare Inn for close to 12 hours and had drunk eight or nine handles of beer during the course of that day.
After the pub closed and he was making his way to a taxi stand he heard people shouting.
"I looked up and saw someone running ... I wouldn't say he was sprinting full but he was coming across the road fairly quickly.
"Something happened in close ... I don't know if it was a push or a punch. It wasn't a big haymaker-type punch but the guy went over and didn't move again."
The victim was bleeding from the head and Morrison had put him in the recovery position and was trying to look after him, Mr O'Malley said.
A recording of the 111 call made by Mr O'Malley was played to the court.
"He's in trouble. This guy ran up to him and punched him from across the road," Mr O'Malley could be heard saying.
A voice in the background said: "No I didn't".
"I saw ya, you ran across the road," Mr O'Malley replied.
He conceded in court that he could not be sure it was a punch.
Ms Smith put to him that he sounded aggressive on the phone and was under the influence of alcohol. He disagreed and said he was thinking clearly.
The trial, before Justice Mark Woolford, is set down for a week.