Eddie Hearn has questioned whether Tyson Fury can fulfil his ambitions of regaining a world heavyweight title after taking 'easy' fights in preparation.
Former world heavyweight champion Fury faces Otto Wallin on Saturday in Las Vegas and claims it will set up a rematch against WBC titleholder Deontay Wilder next year.
"Fury has easy fights that nobody is interested in," said Anthony Joshua's promoter Hearn. "He supposed to be the best heavyweight in the world? Nobody is talking about his fight.
"The interest in Fury is diminishing. It is nearly a year since he fought Wilder and what has happened? Nothing."
Asked if Fury could be tempted to fight Joshua eventually, Hearn said: "Fury is a competitor and is up for a fight, but he's having fights where he cannot get beaten. His profile will dip and his hunger might as well."
Joshua, who hopes to regain the IBF, WBA, and WBO titles from Andy Ruiz on December 7 live on Sky Sports Box Office, has been critical of Fury's choice to take on Wallin.
Joshua said: "I fought Wallin as an amateur. [Wilder and Fury] are the cream of the crop and shouldn't be fighting those type of people. I can't fight Wallin, I don't think I can ever fight lower-tier heavyweights."
Fury defeated Tom Schwarz in two rounds in his most recent fight, after a draw with Wilder.
Sweden's Wallin is unbeaten in 21 fights, and is a year removed from his best result, a victory against his countryman Adrian Granat.
"Otto had a great camp and could not be in a better mental or physical condition," his promoter Dmitriy Salita told Sky Sports.
"He is coming to shock the world - and he is in the mental state to do it."
Wallin said: "[Fury] can do whatever he wants in terms of taking me seriously or not.
"Fury showed a good chin and a lot of heart in that fight [against Wilder], but maybe those shots have taken something out of him."