Deontay Wilder has claimed Anthony Joshua does not have the "courage" to fight him, even as a bout between the pair appears closer than ever.
An undisputed showdown between the two heavyweights failed to materialise in 2018 when they were both still world champions, and talks over a number of years have never been successful.
The two, looking to get back to the top of the division, share a card for the first time on Saturday night, as Joshua fights Otto Wallin and Deontay Wilder takes on Joseph Parker.
It has been reported that Joshua and Wilder will face each other in March next year should they both win this weekend, but the American, who was WBC world champion for five years before his defeats to Tyson Fury, remains unconvinced.
"I don't want to say he's 100% afraid, but I think he's 75%," Wilder said.
On whether the fight will still take place, he added: "We'll see what happens. The future is bright and we are farther [in talks] than we've ever been in history. I can say that with certainty."
It is now Fury and Oleksandr Usyk who hold the belts, after they beat Wilder and Joshua respectively, and the first undisputed heavyweight champion since Lennox Lewis will be crowned on February 17.
Should a rematch take place as expected, it is likely the IBF title would become vacant, with Joshua confirming his desire to fight for that belt and get a shot at becoming a three-time world champion.
He has also insisted he wants to finally face Wilder, who believes both Joshua and his promoter Eddie Hearn are reluctant for the bout to the take place.
"Money hasn't been the issue," Wilder said.
"It comes with not having the heart, the will, the courage to step in the ring. I don't really just blame it on Joshua. I blame it on his handlers, on his promotion and his management. Because let's face it Joshua is the cash cow of the company.
"Without him, no money is drawn into Matchroom. We all know that. Not only do I feel Joshua is intimidated of me, but I feel his promoter is as well. That's why the fight hasn't happened."
