DEONTAY WILDER warned Andy Ruiz Jr he will "splatter" his brain if the pair meet in the ring.
The pair have exchanged trash talk while negotiations continue for a potential fight.
The WBC has ordered a match-up between the duo to determine who will get a world title shot.
Ruiz Jr had wanted to fight Fury but the Gypsy King will instead face Francis Ngannou next in what will be his boxing debut.
While Wilder eyed a clash with Anthony Joshua, which could take place in December or January.
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Now the Bronze Bomber is ready to take on Ruiz Jr, but fired a chilling warning at the former heavyweight champion.
Wilder, 37, said: “With my team, with your team, and now it’s time to put it all together.
“Who acting scared? It isn’t me. You know, because what y ‘all talk about is unreasonable. Let’s face it, and it is what it is.
“So when you serious, holla at me until then. Do what you do, bro. You got a lot of weight to lose, man. You can talk that talk. But only a few walk that walk.
“You know what I mean? So if you want to see what a knockout feels like, get your brain splattered. Holla at me, bro. I’m not far.”
Ruiz, 33, was not intimidated and took Wilder's "fat" insult in his stride.
He fired back a warning that his physique will make him difficult to beat - something Wilder will find out inside the ring.
Ruiz said: “Don’t say motherf***er. You’re mad, wow! F man, why are you mad? My dad’s trying to look out for me. He wants the best for me [and is] trying to give me as much money as I can [get].
“Come on, man. There’s no reason to be f***ing mad about that.
“[You’re] talking about that I’m fat. I got short arms, but then I’m fast. That’s what everybody thinks. That’s what everybody says until they meet me inside the ring.
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“[Well], guess what? — This f***ing fat chubby kid is about to hammer your f***ing a*** down. Let’s get it, baby. Come on!”
