Ali Abdeleaziz, MMA manager, has attacked Jake Paul as a "little prostitute", and threatened to "deal" with him.
Abdeleaziz was critical about Canelo Alvarez's decision to fight Dmity Bvol rather than his client, UFC champion Kamaru Uman.
Eddie Hearn, a boxing promoter, said that he was "embarrassed" by the comments.
Paul was able to agree with Abdelaziz's assessment, but he still called the manager a "rat".
Abdelaziz, who also has UFC legend Khabib Nurmagomedov in his stable, was feisty in his response.
He told MMA Junkie: "You see Eddie Hearn talking s***. This little punk, Jake Paul, and his friends, you see.
READ MORE BOXING STORIES
"I will deal with him because he said certain things. It's funny, because Jake Paul never said certain things about me.
"But then, he suddenly starts to say some things about me and it is clear where this is all coming from.
"I'm going tell you something, somebody will have to pay for the things he said."
Paul, 25 years old, has previously called Usman, 35-years-old, to fight him. Abdelaziz claimed that the American needed the UFC champion's title.
SIGN UP DEALS AND FREE BETS - THE BEST NEW CUSTOMER OFFERINGSAbdelaziz said: "He's pimped. He's a little prostitute.
"They have to bring in MMA and UFC, because they don’t get enough attention. They have to talk about us and I'm humbled.
"Eddie Hern, the entire press conference at Madison Square Garden, talked about me. Good or bad, they still spoke about me.
"And they also talked about Kamaru.
"This little Jake Paul, he's got something in me I promise. He and the one who told him to talk on me.
