Dricus du Plessis has defended his middleweight crown after choking arch rival Israel Adesanya into submission during their gruelling contest at UFC 305 in Perth.

In a bout in which both fighters went all out, du Plessis landed some huge blows late in the fourth round on Sunday to turn the contest in his favour.

A left hook stunned Adesanya, before three rights helped bring him to ground.

Du Plessis then rolled Adesanya over and put on a rear naked choke, with the New Zealander tapping out seconds later.

"This man is the king of getting back up," du Plessis said.

"I'm still alive, that's a bonus.

"I came here to die for this belt and to take a life. I'm still champion, baby."

Adesanya, who was bidding to become the middleweight champion for a third time, believes the loss was just an unexpected chapter of his destiny.

"It's weird how this whole timeline works. It's still destiny," Adesanya said.

"This is not what I planned, this is not what I manifested but I believe in the strangest things.

"Everything happens for a reason, because I've had situations in life not go my way and later on it makes sense as to why it didn't go my way at the time because of certain things that could've happened to me."

And as for the future?

"This is the best I've ever felt. I'm 35, I'm doing the right things. I'm not ... leaving," Adesanya said.

Adesanya and du Plessis had made it clear over the past few months they didn't like each other.

Du Plessis' comment about being the first real African champion, given he was born, bred and still resides in South Africa, riled Nigerian-born Adesanya.

The tension hit fever pitch on the eve of the fight when du Plessis, in response to Adesanya saying he'd take the belt back to Africa if he won, asked whether he would take his servants with him.

The tears flowed from Adesanya after that as he detailed the struggles he and his family endured growing up, before stating: "I can cry and whoop your ass at the same time. On Sunday, I'm going to f***ing kill your dreams."

Du Plessis paid tribute to Adesanya after Sunday's epic fight.

"To share this octagon with a legend, a 100 per cent hall of famer," du Plessis said.

"This man has done so much for this sport.

"I'm sorry that it came across that I disrespected him.

"To share this cage with a legend like that, I have the utmost respect for him, warrior to warrior."

Adesanya was taken down early in the second round as du Plessis attempted to choke his rival into submission.

The New Zealander was able to wriggle his way out of trouble that time around, but it was a different case in the fourth, with Adesanya later conceding he made a major mistake while on the ground.

Earlier in the day, hometown hero Steve Erceg suffered a first-round technical knockout in his flyweight battle against Kiwi Kai Kara-France.

And Australian heavyweight Tai Tuivasa slumped to his fifth consecutive defeat when he was handed a split-decision loss against Suriname's Jairzinho Rozenstruik.