Tyson Fury claims Eddie Hearn is "bitter" because he turned down the chance to join his Matchroom empire.
Hearn labelled Fury "the most unentertaining fighter" he'd ever seen following Anthony Joshua's win over Alexander Povetkin.
Fury is clambering for a fight with his countryman but must first take on world champion Deontay Wilder.
And the 30-year-old claims he rejected Hearn's multi-million pound offer to join his stable.
Fury tweeted: "There is a certain daddy’s boy in boxing who offered me millions of pounds to sign a contract with him! Because he didn't get [the] Gypsy King he now says I’m the worst fighter he has ever seen! Bitter little spoiled punk, #sausage."
Joshua had planned to fight Wilder last weekend but the two champions were unable to agree terms.
Instead he stopped Povetkin in the seventh round at Wembley.
Should Wilder overcome Fury, he could take on Joshua at the national stadium in April.
Hearn said last weekend: "I don't want to be disrespectful, but Tyson Fury is the most unentertaining fighter I've ever seen.
"He's never been in a good fight in his whole career, apart from [Steve] Cunningham, where he got knocked down.
"Deontay Wilder against Anthony Joshua is the biggest fight in world boxing and stylistically it is the most exciting match-up you could possible make in boxing."