Tyson Fury says Oleksandr Usyk is too small to compete with him in their undisputed heavyweight world title fight.

Briton Fury, 35, is the WBC champion, while Ukraine’s Usyk, 36, holds the WBA, WBO and IBF belts.

Fury said former cruiserweight champion Usyk will be “found wanting” on 18 May in Riyadh, Saudi Arabia.

“You can beat the average big ones but you can’t beat the elite big ones,” he said.

“Size is what really matters and we have weight divisions for a reason.”

A former undisputed champion at cruiserweight, Usyk beat Briton Anthony Joshua to become unified heavyweight champion in 2021.

The most recent undisputed heavyweight champion was Britain’s Lennox Lewis in 1999. Fury-Usyk will be the first time in the four-belt era that every title is on the line.

February’s bout was rescheduled after Fury suffered a cut in a freak sparring accident two weeks before the fight.

Fury described himself as an “encyclopaedia in boxing” and listed several cruiserweight greats, including Evander Holyfield and David Haye, who were beaten after stepping up to heavyweight.

He said Usyk’s previous opponents, such as Britain’s Daniel Dubois, had “limited ability”.

“If Tyson Fury can’t beat Usyk, Tyson’s no good. End of,” he said.

“This is my time, my destiny, my era and my generation. Facts.”

After his manager, trainer and promoter predicted a knockout win for Fury, he ended the news conference by joking that Usyk would knock him out in the first round.

Fury’s co-promoter Frank Warren said the fight is the “biggest of the 21st Century”.