Jake Paul learned a tough lesson Thursday night: Don’t step on Mike Tyson’s foot. 

The fighters met Thursday for their final weigh-in before facing off in a highly anticipated matchup at AT&T Stadium Friday night.

But things took a drastic turn when the former heavyweight boxing champion slapped the YouTuber turned boxer on stage. 

Speculation swirled on social media about what might have prompted the legend to snap. 

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Tyson cleared the air, telling the New York Post it was because Paul stepped on his foot, maybe on purpose. 

"I was in my socks, and he had on shoes," Tyson told the outlet after the weigh-in. "He stepped on my toe because he is a f---ing a--hole. I wanted to think it happened by accident. But now I think it may have happened on purpose."

JAKE PAUL’S MOM THREATENS TO ‘KILL’ MIKE TYSON AFTER WEIGH-IN SLAP: ‘F---ING LITTLE B----’

Video of the incident backs up Tyson’s story. 

"I was in a lot of pain. I had to reciprocate," he added.

Tyson, 58, steps back into the ring for the first time in nearly two decades. He will face Paul, who turned to professional boxing just four years ago and has lost just once in 11 bouts. 

The event will be streamed exclusively on Netflix beginning at 8 p.m. ET. According to reports, the main event is not expected to begin until around 11:30 p.m. 

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