"When I'm walking to the ring, that's when I start to feel the switch turn. When I jump into the ring, the switch is on."
He is aware the switch will need to be on against Carlos Takam, a 35-year-old who appears to be in the shape of his life. Takam will enter the ring with a 3kg weight advantage, but there are signs he could also be weighed down by nerves.
Takam refused to answer any questions from the media at yesterday's weigh-in, which played into the hands of the easy-going Parker, who said: "Maybe he's nervous, I'm not sure. Maybe he doesn't get this media attention back home or for any other fight. He's either keeping to himself or he's nervous about [the fight].
"I'm expecting a crazy crowd, a loud crowd. Fighting at home for me is a special feeling. It gives me confidence ... he might see it as pressure for me, but I think the pressure is on him. This might be his last chance to get to a stage like this. He's getting old and he's getting to the end of his career. I'm still a young fighter at the age of 24. There will be many more opportunities but this is the opportunity I want to make a statement at."
A victory in one of the most important fights ever held in New Zealand will make Parker the mandatory challenger for Anthony Joshua's IBF heavyweight title.
After a 12-week camp at his Las Vegas base, Parker feels ready, and he certainly looks it. The key now will be to stay relaxed and to follow a game plan of keeping his distance with his renowned jab. Hitting and moving will be vital against a man who will come forward relentlessly but that in itself will offer Parker, a man with probably the fastest hands in the division, opportunities.
"I'm expecting him to throw a lot of punches and to hunt me down.
"With this fight you're going to see a different focus. I've never fought anyone who brings the pressure that he does or throws the punches that he throws.
"His style suits my style. I have fought guys who have run away and it takes a while to chase them, break them down and finish it. With guys who come forward I have always caught them with good shots and put them away early. We'll see. He's well prepared."