Middleweight UFC champion Dricus du Plessis says he will employ a "win or die trying" attitude when he defends his crown against Israel Adesanya in Perth.

Adesanya is bidding to become a three-time middleweight world champion at UFC 305 on Sunday, while South African du Plessis is defending his title for the first time.

The pair don't like each other, with Adesanya taking particular offence to du Plessis declaring himself as the first real African champion.

Adesanya, who was born in Nigeria but spent a large part of his childhood in New Zealand, took offence to that comment given there had already been a number of champions from Africa, including himself, to have won the title before du Plessis.

Du Plessis claims he is the first real African champion because he was born and bred in Africa, and continues to reside there.

"It's definitely personal for him, because he took a lot of offence in what I said, for speaking the truth, and he didn't like it," du Plessis said of Adesanya's hate for him.

"For me, I stated facts - 100 per cent fact.

"He's angry. I don't care. I'm here for my business, and my business is winning."

Adesanya (24-3, 16KOs) is a well-known UFC star who is widely loved.

Du Plessis (21-2, 9KOs) doesn't have as big a profile, but he doesn't feel he needs a win over Adesanya to prove his worth.

"This fight isn't any bigger to me than any other fight," he said.

"When I step in there, it's the most important fight - and in my mind the last fight I will ever fight in my life.

"I'm going out there to win or die trying.

"So who I fight and what the internet thinks about it, that's got nothing to do with me.

"This (belt) is all the proof I need. I don't need some internet troll or some couch potato to tell me whether I'm good or not.

"This (belt) tells me how great I am."

Adesanya is expected to enjoy the bulk of the support among the sell-out RAC Arena crowd.

But du Plessis will have the entire South African rugby team behind him, with the Springboks to attend the fight the day after taking on the Wallabies at Optus Stadium.

"They are my heroes. It's a massive privilege," du Plessis said.

Adesanya hasn't fought since losing to Sean Strickland in September last year.

The 11-month break allowed Adesanya to heal his battered body and refresh mentally.

Adesanya claims he is now stronger, faster and a far smarter fighter, and is confident he will add du Plessis to his victim list.

Hometown hero Steve Erceg's flyweight battle with New Zealand's Kai Kara-France is also one of the drawcard bouts on Sunday.

Australian heavyweight Tai Tuivasa will take on Jairzinho Rozenstruik in a battle that is expected to end in a knockout.