By Duncan Johnstone

Joseph Parker compared his younger bother John to "a little Mike Tyson" as the young Kiwi prepares for his professional debut.

John, 22, will fight  27-year-old Ratu Dawai from Christchurch over four rounds at a catchweight 85kg on Joseph's undercard in Manukau on Saturday night.

John, a former New Zealand middleweight and light-heavyweight amateur champion, has been sidelined with a wrist injury for the last four years.

But watching the rapid progress of Joseph who has become a world title contender, motivated him to get back in the ring as his own fitness returned.

He has been a constant presence at Joe's side in the final phases of virtually all of his professional heavyweight fights. Now he gets his own chance and says fighting on his brother's card makes his pro debut even more special.

"I'm nervous and excited, I'm really looking forward to this," John said.

"Seeing my brother struggle through the trainings and remembering the times we struggled together (as amateurs) made me want to get back to that time when we did everything together and I was a part of it rather than just helping with it."

Some have suggested John had more potential than his older sibling. Joe remembers John as a dangerous amateur who presented a non-stop attacking approach.

"If I could compare him to someone it would be a little Mike Tyson, because he just went there for the kill," Joe said.

"When the bell rang, it was just like he held his breath for three minutes and threw all his punches and when the bell rang again he'd start breathing again. That's how exciting he was."

John said he'd take a more conservative approach to his pro debut.

"I'm going to take this nice and slow. If I can see I can take the knockout and put on the pressure I will. But I'm not to going to rush into it."

Joe felt that was sensible, remembering his own transition.

"You have to slow things down. As a professional it's about picking your shots, looking for the openings and putting power behind those shots to get rid of your opponent," Joe said.

John has been coached by their father Dempsey for the bulk of his buildup with the polish over the last couple of weeks coming from former WBA middleweight champion Maselino Masoe and Bryan Barry.

But he says he's also learned from viewing his heavyweight brother training and in fights at close range.

"Joe is a huge role model for me as an older brother and as a boxer. To be able to see how has progressed, I've picked up a lot watching him."

Joe believes John is up for this challenge.

"I'm excited. He's been out for a while, he got a bit distracted, but I've seen the focus in him now. He has the skills, he's ready."