Anthony Joshua was involved in an explosive exchange of words with Jarrell "Big Baby" Miller during his news conference alongside Alexander Povetkin in New York on Tuesday.
Miller, the unbeaten American, stormed the stage and started verbally abusing IBF, WBA and WBO heavyweight champion Joshua.
The British boxer -- who usually cuts a calm figure -- turned and squared up to Miller as an expletive-laden exchange ensued.
Joshua can be heard saying: "Who you f---ing talking to?
"Shut the f--- up and get off the stage, you little b----.
"I'll slap you. Have some respect."
Miller was then heard saying that Joshua should "give them what they want," which appeared to be a jibe at his decision to fight Povetkin -- before Joshua and Miller were pulled apart.
Later, Joshua took to social media to ridicule his provoker.
After leaving the stage, Joshua said: "This is where I'm at right now, I can't sit down for too long because there's always people clucking around me feet. I have got to kick them back down."
"People talk about me and see me face-to-face and they still want to talk.
"I defend my titles in the ring time and time again. I just won't tolerate it out of the ring either.
"Anyone is welcome to come and get the smoke as well. Firstly, focus on Povetkin, and you never know what the future holds."
Joshua fights Povetkin in his seventh world title defence at Wembley Stadium on Sept. 22.