Ruiz has gone through an intense training schedule before arriving in Auckland, led by trainer Abel Sanchez. He has lost 27 pounds in two and half months, something he has never done before in his career. He's backing the change of approach.
Big Read: Andy Ruiz training in 35 degree heat to beat Joseph Parker
"It's a different preparation from my other 29 fights. I feel confident," he told the Radio Sport Breakfast.
"I'm actually almost at the same weight but with conditioning and endurance. A lot of people underestimate me with how I look, how I big. I'm naturally big but naturally athlete and I think that's two points on my side. People underestimate me then once they hear the bell, I throw all those fast combinations and they think 'I didn't know this fat boy could do that'.
His opponent on Saturday won't underestimate Ruiz however after learning his lesson during a sparring session three years ago.
Listen: Andy Ruiz Jnr on the Radio Sport Breakfast
Talking about that first sparring session in 2013, Ruiz says he dominated the session so much that Parker couldn't eat for three days after.
"I remember being in the gym and he was walking in like 'really I'm going to spar this guy, that boy, this chubby kid' and what do you know, I end up lighting him up. He got a big surprise," Ruiz said.
On that day Ruiz said he used Parker's biggest weapon, his jab, against him.
"It's pretty quick but the thing is I would counter-punch him every time. When he would throw he would leave himself open there and that's when I would react and throw my combinations and that's how I was getting him. A lot of things have changed. He's had more fights and I've had more fights and I think it's going to be an interesting fight. A lot of fireworks."
