Tommy Fury believes he can knock Jake Paul out in the first round when the pair meet next month.
The duo took part in a press conference on Wednesday, which was remarkably bad-tempered, ahead of their December 18 clash in Florida.
"Talking doesn't win fights," Fury said. "I'm not engaged in all this because I don't care. I'm not using Instagram because I don't care. When he jumps through the ropes he will realize that I'm not a YouTuber."
Tyson Fury, who is currently training his brother, joined in to say: "Poor old Jake Paul will get severely knocked out. "[Jake and Logan Paul] are not fighters. Tommy will knock him into next week."
Paul replied: "He doesn't have a chin. He's never been hit hard by anybody. He has fought nobody. He couldn't crack an egg!"
Tommy Fury predicted: "When he gets in the ring with me, he will find his level. He'll be out in the first round."
Both fighters take undefeated records into their fight. Tommy Fury has seven fights and seven wins, while Paul has four from four, though neither of them dominated their last fights when they appeared on the same card for Paul’s clash with Tyron Woodley. Paul beat Woodley via split-decision while Fury looked lackluster in the main card opener, defeating Paul training partner and former MMA fighter Anthony Taylor via unanimous decision.