You're not going to "belieb" this.

On Sunday, Justin Bieber challenged Tom Cruise to a fight in “the octagon” and appeared to try and provoke the actor, saying if he doesn’t accept he’ll “never live it down.”

The tweet went viral and MMA fighter Conor McGregor announced that his company would host the fight. McGregor also appeared to take a shot at Cruise and said the fight would only go on if he’s “man enough to accept this challenge.”

The “Mission Impossible” star did not comment on the posts, but it appeared that many on social media believe Cruise would dispatch the “Baby” singer with ease. Odds Shark, a source for online handicapping, said, “We don’t like your odds, Justin." Bobby Nash, an MMA fighter called out the singer, “You’re calling out a 56 year old man lol.”

Cruise stands at 5’ 7 and weighs 170 pounds. He is famous for doing most of his own stunts and maintaining an enviable physique. He appears ready and willing to fight on screen and often does so while falling from a plane.

Bieber reportedly has two inches on Cruise but weighs 145.5 pounds, according to reports.

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“I would love to see this exhibition,” Diego Sanchez, another MMA fighter posted.