Tyson Fury doubts Anthony Joshua's knockout power and claims his heavyweight rival has a confidence issue, having avoided fighting him "for a long time".
The two British boxers appear on course to finally face each other after Joshua was victorious over Kubrat Pulev in December, stopping the Bulgarian in the ninth round of their bout at Wembley Arena.
Both sides agreed in principle to a two-fight deal for 2021, though details over a date and venue for an initial bout are still being discussed.
After seeing off Pulev, IBF, WBA and WBO champion Joshua vowed to beat Fury when they finally go toe to toe, insisting he will take his "head off his shoulders" in the long-awaited showdown.
However, in an interview with Fox Miami, the holder of the WBC title questioned Joshua's ability to back up his words.
"I don't think he's as good as people crack him up to be, or he doesn't believe he is, his own self. He's got a confidence issue," Fury said.
"The fight has been brewing for a long time. They've been avoiding me for a long time. Now it's finally got to happen.
"I've never seen him take anybody's head off anybody's shoulders in all of his 22 fights. It's probably a lie, another lie. We'll see if he's got the guts to try and do it."
Fury had hoped to get in a bout before the end of 2020 - a year in which the boxing schedule was badly hampered due to the impact of the coronavirus pandemic - only to shelve that plan.
The 32-year-old has not fought since February of last year, when he sensationally stopped the previously unbeaten Deontay Wilder in their rematch in Las Vegas.