British heavyweight Dereck Chisora will take on former undisputed cruiserweight champion Oleksandr Usyk at London's O2 Arena on May 23.
Usyk reigned supreme at the 200lbs weight limit, unifying all four of the major world titles in the World Boxing Super Series before successfully defending his belts against Tony Bellew in Manchester in November 2018.
Since stepping up to heavyweight, his only fight was a comfortable victory over faded American contender Chazz Witherspoon in October last year, and he is set to have his first acid test in the blue riband division.
Chisora, 36, may have lost nine of his 41 professional bouts but is enjoying a late career resurgence, winning his last three fights since being viciously knocked out by domestic rival Dillian Whyte in December 2018.
Usyk is the mandatory challenger for the WBO heavyweight title held by Anthony Joshua but the Ukrainian, who has won all 17 of his bouts in the paid ranks, must get past Chisora before contemplating a tilt at world honours.
"Usyk reckons he can step up and survive with the big boys," Chisora said following official confirmation of a bout that was expected to take place this month but was delayed because of an elbow injury to Usyk.
"He may be the undisputed cruiserweight champion of the world but on May 23 he will find out what it feels like to be hit by a real heavyweight.
"I'm going to remind him exactly why he hid in the cruiserweight division and also get revenge for my boy, Tony Bellew. This will be war."
Usyk may be travelling to his opponent's back yard but he has fond memories of the English capital, having won heavyweight gold at London 2012 before turning professional the following year.
The 33-year-old said: "Boxing in Manchester in 2018 was an amazing experience, now I get to do it in London at the famous O2 Arena and I can't wait to fight in front of the British fans once again.
"As a cruiserweight, I reached the highest heights as undisputed champion and now I am following the same path as a heavyweight.
"I expect a real test in Chisora – he is strong, tough and resilient. I recall being an amateur and watching his fight with Vitali Klitschko (for the WBC heavyweight title in 2012). It seemed so big and far away.
"Now I am myself taking a fight against Chisora. I am working hard in my training camp to show a spectacular performance."