Tuitupou punched the officer's face and as the policeman stumbled back, desperately trying to reach for his pepper spray, he was punched twice more.
A flurry of blows ensued before the officer eventually hit the pavement.
"I could fell the punches landing to the back of my head before I hit the ground," the senior constable said.
While lying helpless on the ground, Tuitupou's co-attacker Tupou Kaufusi stabbed the officer through his stab-proof vest with a screwdriver.
"I remember waiting for the final punch which would have been lights out," the officer said. "I was lying on the ground in a pool of my own blood."
The attack lasted about 30 seconds.
A passing truck driver, noticing the assault, stopped to help the policeman, while Tuitupou and Kaufusi fled the scene.
The officer was taken to Middlemore Hospital, suffering from a stab wound, a fractured rib and several other injuries.
Tuitupou and Kaufusi were arrested and charged the next day.
"I am not the same person anymore and my wife would agree ... I now approach every car with a sense of mistrust," the officer said in his statement.
He said his young daughter was also affected by his injuries, which has left him with lasting psychological and physical harm.
Tuitupou, who was charged with injuring with intent to injure, assault and breaching his parole, said he was "wasted" from alcohol at the time of the attack.
He has previous convictions for robbery in 2014, disorderly conduct in 2013, and assault and possession of a knife in 2012.
The officer was in court for the sentencing and supported by several of his colleagues.
Kaufusi, an 18-year-old builder, will be sentenced in September.