Just when you thought the celebrity fighting challenges phase was over, another man has thrown his name into the mix.

The internet blew up last month when Justin Bieber seemingly challenged acting sensation Tom Cruise to a fight inside the UFC Octagon.

In an early June tweet, Bieber said: "I wanna challenge Tom Cruise to fight in the octagon. Tom if you dont take this fight your scared and you will never live it down. Who is willing to put on the fight? @Danawhite?"

It sparked huge interest from the public, with both names trending worldwide on Twitter and much intrigue as to what would really happen if the two really did have a scrap.

UFC President Dana White actually confirmed this week that he received a phone call from two people who stated the fight could possibly still happen, despite Bieber backtracking just a few days after his call-out of Cruise.

It would surely break box office records, but it still seems unlikely that it will actually take place.

Thankfully for Bieber though, another celebrity has thrown his name into the mix for a potential MMA bout.

Steve-O, the star of comedy television series Jackass, says he is tired of being overlooked and has officially thrown down the gauntlet to the Canadian singing star.

And when he spoke to TMZ this past weekend, Steve-O claimed he had already discussed with Dana White about a potential fight with Bieber.

"I had a little chat with Dana White, and he agreed that if Tom Cruise doesn't step up, and someone needs to fill the cage with Justin Bieber, then I'm the guy," said Steve-O.

"We shook on it, me and Dana White."

Steve-O then dished out some verbals to Bieber, saying: "I think you've been picking a fight with the wrong guy. Tom Cruise might be 56, but, hey, I'm 45!"

Whilst Steve-O v Bieber may not make the numbers that Cruise v Bieber would, any two celebrities going at it in a battle of MMA talents is a must-see moment.