Interim champion Israel Adesanya has dethroned UFC middleweight champion Robert Whittaker with a stunning knockout in the second round of their highly anticipated 185-pound unification bout which headlined UFC 243 in Melbourne.
New Zealand-based Adesanya landed a right hook which floored Whittaker in the final seconds of the first round and ended the fight in the second of the five-round contest with a left hook.
In all it took Adesanya 3 minutes 35 seconds.
It was New Zealand-born Australian Whittaker's first fight since June 2018 in Chicago. The 28-year-old Whittaker was scheduled to fight in February but withdrew due to emergency bowel surgery.
The show on Sunday attracted a UFC world-record crowd of 57,127, eclipsing the previous best of 56,214 at the same venue for UFC 193.
"Hats off to Adesanya, a great striker," Whittaker said.
"I felt I was doing pretty well until you get caught.
"I'm only 28. I've still got a fight or two yet ... I'm not going anywhere."
Neither man landed a lot in the first round until Adesanya's big right at the end.
The Nigerian-born fighter showed great evasive skills, avoiding plenty of kicks and punches, though Whittaker did land a few right hand strikes.
"He threw everything we expected," Adesanya said.
"We had everything planned for plan A to Z. It's unreal, they said I have no knockout power.
"He caught me with a nice one but I returned. I eat it but give it back two times.
"I hate to get hit. It's stupid to get hit. I'm tough and smart. At the end of the day, my team and I were smart."
Interim champion Adesanya improved his MMA record to 18-0 and won the undisputed title in just his seventh UFC bout, all of them inside the past two years.
It was Whittaker's first loss in 10 bouts and in more than five years, with his MMA record dropping to 20-5.
In the build-up to the main fight two of Adesanya's City Kickboxing team-mates had wins.
New Zealand fighter Brad Riddell kicked off his UFC career in thrilling fashion with a unanimous decision victory over Australian Jamie Mullarkey, while Dan Hooker dominated his opponent Al Iaquinta to win in three rounds.
Hamilton's Luke Jumeau suffered a split decision defeat to Brazilian Dhiego Lima on the main card.