Tyson Fury's manager Frank Warren has questioned rival Anthony Joshua's ability to regain his place among the world's leading heavyweight boxers.
Warren urged the Londoner not to take a rematch with Andy Ruiz Jr, who defeated him in New York earlier this month as a late replacement following Jarrell Miller's positive drug test.
"I do have my doubts," Warren told BBC 5 Live's Sportsweek. "I don't think he should take the rematch. Maybe he should take some time out and regroup, I don't know.
"That's his decision. But he'll be fighting a guy who next time will have more than five weeks' notice and go into a proper training camp.
"I'm not going to say or make any predictions about the shape of his body, but he's got fast hands and I believe he's got Joshua's number.
"He's taken Joshua's best shot and he knows he has the punching power to do damage to Anthony Joshua."
Warren said he did not know who Fury will fight next, but that it would be someone "in the top five" - adding that he expects the British boxer to fight American Deontay Wilder early next year.
Fury said after his second-round stoppage of Germany's Tom Schwarz in Las Vegas on Saturday night that dates of September 21 or October 5 had been agreed in principle for his next bout.
"First of all we'll see who's available and we'll work on that over the next week and we'll make it happen," Warren said. "I genuinely do not have a name at the moment.
"It's highly probable that [Wilder v Fury] fight will happen early next year.
"I can't go into the details. I don't think the problem is the money, all parties want to make this fight happen."