All of the hype and pageantry of an impending Conor McGregor return to the UFC Octagon on Saturday night blew up in smoke within seconds.

McGregor stepped into the cage against Max Holloway at UFC 329. He came across the mat with a flying left roundhouse kick and landed awkwardly on his right knee. He tried another kick and slipped to the ground. He tried to power through it but nearly two minutes into the fight, he grabbed at his right leg again and referee Mike Beltran called the fight.

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“My head gasket is gone,” he wrote on social media. “Destroyed. I had no injury / injuries going into the fight. I was throwing kicks, planted and jumping, all throughout camp as well as backstage before the fight. This came out of nowhere.

“I am beyond dark here. I can only describe it as hell.”

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UFC president Dana White said there were no signs of a pre-existing injury going into the weigh-ins on Friday.

“Five years off in this sport is rough,” White said. “We’re assuming a blown ACL. That’s what I assumed when I saw it, and that’s what the doctors think, too.”

Holloway said he kept telling Beltran to stop the fight because McGregor was injured but the Irishman kept saying, “Fight!”

“During the fight, you could see his demeanor change,” Holloway said. “When I saw him hurt, I said, ‘Call this, he’s hurt.’ I just hope for a speedy recovery.”

McGregor was participating in his first bout since July 2021 when he lost to Dustin Poirier due to a devastating leg injury. He’s only won one fight since 2020.

The Associated Press contributed to this report.