Jake Paul would have looked like Oleksandr Usyk inside the ring if he fought Tommy Fury, claims the Brit's former opponent Anthony Taylor.
Fury pulled out of facing Paul, and has been replaced by Tyron Woodley on Saturday night, due to "a severe chest infection and a broken rib".
YouTuber-turned-boxer Paul called Fury's withdrawal an "embarrassment," while Taylor also aimed a verbal attack at the British contender, who defeated him on points in August.
"He's a novice. He just had height on me," said Taylor, who has also sparred with Paul. "He doesn't have knockout power.
"If Jake fought Tommy, it would have been the same fight as Anthony Joshua vs Oleksandr Usyk. Usyk moves like Jake moves. Jake, against Tyron Woodley, touched every corner and crevice of that ring.
"Jake has better cardio than Tommy. His IQ and his awareness are better."
Taylor claimed about Fury's withdrawal from fighting Paul: "The real reason is that his conditioning was not on point.
"I fought Tommy - his cardio was bare, even in important rounds. He had six weeks to get into shape but it takes longer than that.
"Big John Fury knew that and, I guarantee, he pulled the trigger on this fight because he didn't trust Tommy's cardio."
Tommy Fury defeated Taylor on the undercard to Paul's split decision victory over Woodley.
The withdrawal of Fury, who is undefeated in seven fights, means that Paul will now face Woodley instead in a rematch this weekend.
"Tommy has no shame. He is not a prideful man," Taylor said. "He's not Tyson Fury. Tommy is a good kid, young and upcoming, maybe a world champion in seven years' time.
"But now? He's in over his head. His dad and Tyson are talking him up. He is a level behind Jake in terms of his trash talk and his boxing."
Paul has suggested that he may think twice before revisiting a fight with Fury next year.
Asked if he expected Paul to ever face Fury, Taylor said: "No. Facts. Because Tommy does not promote well. He isn't a promotable guy.
"He is only good for getting Tyson into the same room!"
Sky Sports Boxing schedule
Saturday December 18 - Top Rank in Montreal
Artur Beterbiev vs Marcus Browne - IBF and WBC light-heavyweight titles
Saturday January 29 - BOXXER in Cardiff
Chris Eubank Jr vs Liam Williams
Claressa Shields vs Ema Kozin - IBF, WBA and WBC middleweight titles
Saturday February 19 - BOXXER in Manchester - Sky Sports Box Office
Amir Khan vs Kell Brook
Saturday February 26 - Top Rank in Glasgow
Josh Taylor vs Jack Catterall - undisputed super-lightweight titles