Dillian Whyte believes Anthony Joshua's exchanges with Tyson Fury over sparring prove he "just talks rubbish".
In a detailed critique, heavyweight contender Whyte hit out at WBA, IBF and WBO champion Joshua, saying he is a changed fighter who has lost his aggressiveness.
Whyte believes his fellow Briton, with whom he shares a promoter in Eddie Hearn, always backtracks after making comments in the same way Fury and Deontay Wilder do.
He cited the example of Joshua's recent exchanges with Fury, offering to help him with sparring sessions ahead of his WBC title rematch with Wilder next month.
Whyte told Sky Sports of Joshua: "He's a good fighter and a good champion, but he talks a lot of rubbish most of the time.
"Him, Wilder, Fury, they all talk the same rubbish. He says one thing and then he backtracks and says another thing. At least I'm consistent with what I say, and I do what I say.
"One minute he says, 'I'm going to spar with Fury' and then the next minute he says, 'If it works in my schedule'. When Fury said, 'Yes, if it works in my schedule'. He just talks rubbish, man.
"I'm here, I'm ready to fight, if he [Joshua] wants to fight me, the fight can happen."
Whyte, who has been touted for a fight with Russian Alexander Povetkin, has not been impressed by the evolution of a man who knocked him out after seven rounds of their domestic grudge match in December 2015.
He believes Joshua will be forever marked by his initial loss to Andy Ruiz Jr. in June 2019, but feels signs of a more conservative approach were already apparent before his two contests with the Mexican.
"We've seen this before - Lennox Lewis was an aggressive fighter on the front foot but got knocked out by Hasim Rahman, then changed his style," added Whyte.
"Joshua will be the same. Tall heavyweights start their careers very aggressively, but then?
"Let's go further back - Carlos Takam, Alexander Povetkin, Joseph Parker. There were signs of caginess and not liking getting hit.
"Even Deontay Wilder, when he was clocked a couple of times by Luis Ortiz, he thought 'I'm just going to wait'.
"We have seen this time and time again in history, and it's always the same."
After winning his titles back against Ruiz in December, Joshua looks poised to defend his belts against IBF mandatory challenger Kubrat Pulev next as Whyte's wait for a title shot goes on.