Miroslav Jovanavic, 55, went on trial on Wednesday for allegedly using a utility knife to repeatedly stab the man in April last year.

Prosecutors say the attack left the man with a collapsed lung, a severed artery, and caused major blood loss.

The Crown used its opening submission to the jury on Wednesday morning to describe the stabbing as unprovoked, saying Mr Jovanavic had walked up behind the man.

Jovanavic allegedly punched the man in the back of the head, and the pair then struggled, before Jovanavic put him in a headlock.

The complainant was allegedly stabbed repeatedly with the small knife, before the pair separated.

The prosecution say Mr Jovanavic's alleged attack was motivated by revenge. The pair knew each other, having lived in the same apartment block previously, the court heard.

Mr Jovanavic's son had served time in a prison cottage with the victim, and the pair had been involved in a fight during their incarceration.

But Mr Jovanavic's counsel, James Lawton, said his client had acted in self-defence, and told the jury they would hear conflicting accounts about who had the knife, where the weapon came from, and where it went after the fight.

Mr Lawton said the alleged victim had walked up to Mr Jovanavic in the bus interchange earlier, and said something like, ''I should cut your head off''. He said the milliseconds after Mr Jovanavic punched the man in the back of the head were crucial in determining who had the knife, and whether his client had been acting in self-defence.

The complainant gave evidence from a remote witness room on Wednesday. He said he had not owned the knife, and said he did not have a weapon at the bus interchange. ''Definitely not, I was not armed in any way,'' he said.

The man told the court that Mr Jovanavic was threatening him during the confrontation.

''He had it at my eyes, saying he should take out my eyes.''

He said he pleaded with Mr Jovanavic to stop, and told him he was sorry for the fight with his son.

He said he felt like he was in shock and was bleeding out as he waited for the ambulance to get to the scene.

''At the time, I felt like I was dying. I knew I was dying.''

His partner, who was present during the confrontation, also gave evidence on Wednesday.

Mr Lawton cross-examined her on whether her partner had the knife with him on that day.

She was questioned over her description of the knife to the police as a ''Leatherman'', despite saying she had never seen the knife before the alleged stabbing.

The trial continues on Thursday.