South African Dricus du Plessis defended his UFC middleweight title on Sunday after a fourth-round submission win over bitter rival Israel Adesanya in a blockbuster bout at Perth Arena. 

In the main event of UFC 305, du Plessis appeared to be flagging against the two-time former champion before a spectacular takedown of Adesanya solidified his 185-pound belt. 

Du Plessis (22-2) has now won 10 fights in a row, having originally claimed the belt after beating polarising Sean Strickland in January.

"I came in here to die for this belt," du Plessis said. "I came here to take it home. Here I am, still the champion." 

At a sold-out 15,000 Perth Arena, Adesanya (24-4) enjoyed significant crowd support and seemed to have an edge for much of the fight until he was helpless against du Plessis' rear-naked choke. 

"I'm disappointed, but at the same time I'm proud because this is the best I've felt and looked," said the Nigeria-born New Zealander, who made his return after a shock defeat to Strickland in September last year.

"I just had the better man on the night and I'll give him respect for that."

Du Plessis was accompanied into the Octagon by South Africa rugby captain Siya Kolisi and second-rower Eben Etzebeth, with his country's national anthem thundering around the venue. 

There was much anticipation over the bout after the fighters had engaged in a war of words in the build-up. 

They were meant to fight in Sydney last year, but du Plessis was unavailable due to injury. 

It was a measured start amid a febrile atmosphere with the taller Adesanya, a former kickboxer, using his longer reach to fend off the aggression of du Plessis. 

Adesanya aimed to counterstrike and he utilised his favoured kicks to deadly effect, as du Plessis emerged bloodied on his forehead.

Du Plessis unleashed a powerful left-handed punch late in the first round and his momentum continued in the next when he landed a big takedown and had control on Adesanya's back.

But he could not lock in a submission as Adesanya worked his way back into the fight with grappling. 

Adesanya's strategy of wearing down du Plessis appeared to take effect by the fourth round as he landed cleaner punches. 

But du Plessis mustered energy and a rattling blow wobbled Adesanya as the South African soon emerged triumphant. 

Also on the main card, Kai Kara-France stunned the partisan crowd by pummelling Australian Steve Erceg in a first round-knockout in the flyweight. 

The New Zealander was in an aggressive mood and twice dropped a hapless Erceg with a flurry of powerful punches. 

"I knew Steve was going to be crafty and smart, so I had to set it up... and be smart and that's when I went for the finish," said the 31-year-old Kara-France. 

In the heavyweight bout, Jairzinho Rozenstruik of Suriname beat Australian Tai Tuivasa by split decision.