The greatest upset in UFC middleweight title fight history belongs to Sean Strickland.

Strickland (28-5) stunned the mixed martial arts world on Saturday, as he claimed the 185-pound championship in a five-round decision over arguably the greatest middleweight of all time in Israel Adesanya. The middleweight title fight headlined UFC 293 inside Qudos Bank Arena in Sydney.

Going into Saturday, the biggest upset in middleweight title fight history belonged to Michael Bisping, who famously knocked out Luke Rockhold in a short-notice fight in 2016. Strickland's victory was far less probable, according to betting odds: He was a +500 underdog to Adesanya, making it the largest betting upset ever in a UFC middleweight title fight (Bisping was +400 against Rockhold).

And the way in which he did it -- convincingly, over the course of five rounds -- made it even more unbelievable.

"Am I f---ing dreaming?" asked Strickland, who earned 49-46 scores from all three judges. "Am I going to wake up? Somebody hit me. Literally, never in a million years did I think I was going to be here.

"Izzy is a bad mother f---er. You don't fight a guy with that many highlight-reel KOs. The majority of my friends, he's beat pretty easy. I was even kind of doubting myself at times."

Adesanya was making the first defense of his second reign as middleweight champion. He regained the 185-pound belt in April with a knockout of Alex Pereira.

Adesanya made no excuses for his loss during a brief appearance at the postfight news conference Saturday, before leaving his coach, Eugene Bareman, to take questions from reporters.

"I had a different plan for this, but life throws curveballs at you," Adesanya said. "Win or lose, I wasn't going to say much anyway, but right now, I lost tonight to the better man on the night and I just want to be with people who care about me, my team, so I'm going to go do that."

UFC president Dana White said he "absolutely" thinks a Strickland-Adesanya rematch is in order.

"The rematch is interesting," White said. "That could be the thing, too. You go into the Pereira fight, it's such a big fight, and then you overlook Strickland? I don't know the answers to these questions, but Israel does and I'm looking forward to hearing them."

According to UFC Stats, Strickland outlanded Adesanya 137-94 in total strikes. He dropped Adesanya with a right hand in the opening round, becoming the first fighter to ever do so in the UFC. Even when Adesanya (24-3) suffered a TKO loss to Pereira in their first UFC fight in 2022, Pereira never knocked him down.

A former welterweight, Strickland, 32, wasn't even supposed to be challenging Adesanya on Saturday. The UFC originally looked at a championship fight between Adesanya and South Africa's Dricus du Plessis, but du Plessis was unable to accept the fight due to injury. Adesanya campaigned for Strickland to take du Plessis' place.

That proved to be a mistake, as Strickland essentially neutralized the defending champion's offense. Other than a couple of minutes in the second round, Adesanya looked uncomfortable and unsure of his weapons, even in a fight that never touched the floor. The majority of the shots he landed were glancing, and Strickland showed very little wear and tear after 25 minutes.

Strickland, who was born in California and now trains out of Las Vegas, yelled in Adesanya's direction during the final minute of the fight. He'd spent most of the championship fight buildup taunting and insulting Adesanya, who helped him land the opportunity in the first place.

Adesanya, who has now lost twice in the span of three fights, graciously accepted the defeat. He raised Strickland's arm once the results were read, and then exited the Octagon.

Stylistically, there was nothing surprising about Strickland's approach. He is well-known for his plodding, upright boxing style. His defense was perhaps a bit overlooked, however, as he did enter the contest with the best striking defense of any active UFC middleweight. Unofficially, he defended 65% of Adesanya's strike attempts on Saturday.

ESPN ranked Adesanya the No. 4 pound-for-pound fighter in the world going into UFC 293. Strickland was the UFC's No. 5-ranked middleweight and was only 2-2 in his past four bouts.