Tyson Fury believes Oleksandr Usyk would be a "lamb to the slaughter" against the world's elite heavyweights.
Usyk outpointed Derek Chisora last month in his second outing in boxing's premier division.
He is now guaranteed a shot at champion Anthony Joshua - although the Brit is set to vacate his belt in order to face Fury.
Fury, however, does not believe Usyk has the ability to trouble the best in the business.
"Did we see the best Oleksandr Usyk at heavyweight? I don’t know," he told talkSPORT.
"But on that performance I can say that none of the top 15 heavyweights out there are sweating Oleksandr Usyk at the moment, unfortunately.
"None of us are quaking. Is that it? Everyone’s like, 'Is that what all the hype was about?'
"This is the heavyweight game and heavyweights ain't like they were years ago, and Chisora’s probably the smallest heavyweight out there.
"Being brutally honest, I think when he fights a big heavyweight who can punch a bit it’ll be like a lamb to slaughter.
"My opinion of it is – it’s the heavyweight division and not the cruiserweight division for a reason.
"I understand look, all cruiserweights that do well want to step up to heavyweight to get that big money. They all want a piece of the pie, but there’s divisions for a reason.
"After his last performance, I honestly thought he was better than he was because I highly rated Oleksandr Usyk as a master technician as a cruiserweight.
"But at heavyweight there was nothing that impressed me to be fair."
Fury is due to return to action at the Royal Albert Hall on December 5 when he defends his world title against Agit Kabayel.
He will the pursue a unification clash with Joshua, assuming his rival beats Kubrat Pulev a week later.
