In a brief opening statement, Kiwi's lawyer Gene Tomlinson said it was not Warren Kiwi but his brother Graeme who had pulled the trigger when Nyman was shot.
Nyman testified he was halted in his tracks as he walked down his driveway on the day he was shot at by a voice telling him to "hold it right there".
"I turned around, there was someone pointing a rifle at me, I was looking right down the barrel, he was no more than a metre from me. I said 'what the f*** do you want?' He was balaclavaed up, told me to get into the shrubbery. I said 'who sent you?, did JC send you?' He told me to **** up, to turn around but I didn't.
"I told him either shoot me while I'm looking at you because if I get that gun, I'll shoot you."
Nyman said he dropped the chilly bin he was holding, grabbed the gun and, as the pair wrestled, he flipped the gunman over his head. Both lost their grips on the rifle as they fell, the other man reached it first. A shot was fired.
Nyman described running to his porch and hearing the sound of a bullet being fired.
"I felt a burning sensation. I knew I had been shot, I was shot in the bicep. I was yelling at my partner to call the cops."
The pair again wrestled their way down the driveway with both gripping the rifle.
"I still had hold of it at that point, it was pretty much under his chin I was about to push my finger into the trigger guard, he got his finger onto the trigger, I didn't know if a bullet was loaded into the breach."
When they reached his truck, Nyman rammed his opponent into the grille several times.
He outlined how he had aimed at the other man with the intention of shooting him but his partner had pleaded with him not to shoot as the police were on the way.
Nyman told Crown prosecutor Chris Macklin, "the fullah" was no pushover.
"I had to use everything I had. I am used to that playing rugby, but I was pretty spent."
Before the shooter ran off he apologised at least half a dozen times saying "wrong house, wrong fella, wrong street".
Questioned by Kiwi's lawyer, Gene Tomlinson, Nyman acknowledged he had managed to grab the defendant's balaclava but it was so tightly laced he was unable to wrench it off.
He reiterated his earlier evidence that the man had such bad body odour it was as if he had not washed for a couple of days. He agreed with the lawyer he had told police the man's breath smelt like a dog's.
Nyman's partner Andrea Swinton recounted hearing him banging on their door yelling at her to call the police. She turned on the light, opened the door and saw a gunman with a rifle trained on Nyman
"I could see blood on the porch but I couldn't see what was going on, I was really confused then I realised he [Nyman] had already been shot, there was blood on him."
She described seeing the two fighting their way down the driveway and her partner getting the better of the gunman.
"It looked like Karl was going to shoot him, I yelled at him 'don't shoot him, the cops are coming', all I wanted was to get him back inside, I didn't want him to chase after that guy."
The trial, which is before Justice Pheroze Jagose and a jury of four men and eight women, is expected to last two weeks.