Melbourne (AFP) - Undisputed lightweight world champion Devin Haney says he has “all the answers” to George Kambosos as they clash in a title rematch in Melbourne on Sunday.

The unbeaten American toppled the Australian on unanimous points in June to become the first undisputed lightweight champion in modern boxing history, since Pernell Whitaker in 1990.

A rematch was in his contract and they will meet again at Rod Laver Arena, best known as centre court for the Australian Open tennis and significantly smaller than the 41,000-capacity Marvel Stadium that hosted the first bout.

“Obviously he’s going to come in with a better game plan, so I’m going to need to be better than I was last time,” Haney, who has a 28-0 record with 15 KOs, told reporters.

“Life hasn’t changed. Of course I have the belts. I worked hard for it, and I knew the time would come, so nothing has changed. Now it’s time to defend and come out victorious.”

Kambosos was outclassed by Haney’s speed, instinct and relentless left jab in June in what was a defensive masterclass by the American.

Haney, 23, said he had “tunnel vision” on winning again and could cope with whatever the Australian brings.

“I can’t say what he can do differently because I have all the answers for anything he brings to the table,” he said.

“We’ve been studying him like crazy. We know what he does. We know the mistakes that he makes and the habits that he has.”

- ‘Do or die’ -

The win last time elevated Haney to an exclusive club of fighters, becoming only the eighth boxer to hold all four belts from the major sanctioning bodies – WBC, WBA, IBF and WBO –- at the same time.

Defeat was Kambosos’s first in 21 bouts since making his professional debut in 2013.

He entered the fight in a blaze of publicity, boasting about his credentials and talking down Haney, an approach he now admits detracted from what he was there to do – defend his IBF, WBA and WBO belts and win the WBC one Haney held.

“Instead of staying focused on winning, on what got me to the title, I got caught up in trying to make myself a bigger brand,” the heavily tattooed 29-year-old father-of-three said.

“In the lead-up to that last fight, every day the gym was packed. There was media all the time, too. And I just couldn’t focus.”

This time he has had low-key preparations to get “zoned in”.

“So Haney can say what he likes in the build-up. Social media can say whatever it likes, too. Nothing will break my focus,” he told reporters.

When the fight was announced, Kambosos suggested that if he doesn’t win, he could retire, calling it “do or die”.

The undercard is led by two-time world title challenger Jason Moloney of Australia battling Thailand’s Nawaphon Kaikanha in the final eliminator for the WBC bantamweight title.