Tyson Fury believes Anthony Joshua has a confidence problem after "shaky performances" and claims he could beat his British rival inside two rounds.
A fight between the two men who hold the four major world heavyweight titles is being negotiated by their teams.
After beating Kubrat Pulev in December, Joshua told reporters he wants to take Fury's "head off his shoulders".
Fury, 32, told Fox Miami: "On his last two fights, he's not in form. On mine, I am, so momentum is with me."
He added: "I just believe, take him out early - very early - maybe even one round or two rounds.
"I don't believe he's as good as people crack him up to be, or he doesn't believe he is in his own self.
"He's got a confidence issue. He's coming off two shaky performances and boxing is all about who is in form and who isn't."
Joshua's 'lose-lose' situation
Fury holds the WBC world title, while 31-year-old Joshua is in possession of the IBF, WBO and WBA belts, meaning all four could be contested in a heavyweight fight for the first time.
A percentage split of the money the fight could generate is said to be agreed between the pair.
But there are wider issues to iron out such as where the fight will take place - which will in turn impact the level of money made - as well as how rival broadcasters can work together.
"Whenever the world gets back to normal, whatever normal may consist of after this pandemic, then that's when this fight is going to happen," Fury added.
"This fight has been brewing for a long time. They've been avoiding me for a long time and now it's finally got to happen.
"We saw the Floyd Mayweather v Manny Pacquiao fight, we were waiting for that fight for 10 years. When it finally happened, I believe Pacquiao was past his best. It maybe should have happened four or five years earlier.
"So hopefully we get to go one-on-one combat with not only the two best heavyweights out there but two heavyweights who are in their prime and not past it."
Analysis - Is the historic night close?
BBC Sport boxing reporter Luke Reddy
In the aftermath of Joshua's December win over Pulev, his promoter Eddie Hearn said the finer details over a Joshua-Fury fight could be sorted in a couple of days. Almost a month has now ticked by.
It is interesting to hear Fury himself use terms like "hopefully" when discussing the fight happening. It points to some doubt.
The gate receipts from Fury's February win over Deontay Wilder hit $17m, so staging something with no crowd seems highly unlikely.
Both Fury and Joshua are talking a good game for how a fight could play out. It is the night boxing longs for in 2021 but there are problems to solve before punches can be thrown.
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