Usyk is regarded as one of the very best fighters of this modern era. He had a superb amateur career, before becoming a unified world champion at cruiserweight.
His last fight in that weight class came in November 2018 against Tony Bellew. It was a great fight at Manchester Arena, but Usyk eventually got the better of the Liverpudlian, knocking him out in the eighth round.
The Ukrainian has since moved up to heavyweight and is set for his second fight in his new division on Saturday night against Bellew's close friend, Derek Chisora.
Usyk beat Chazz Witherspoon in his first heavyweight bout, but this fight against 'Del Boy' is a much bigger test for him.
Fans and pundits alike have been quick to question Usyk's credentials at heavyweight, with him being much smaller than the likes of Anthony Joshua and Tyson Fury.
There is no doubting his ability, as he is one of the most gifted boxers around today. But Bellew told Fight Night on talkSPORT that his former opponent will come unstuck if he ever faces Joshua or Fury:
"First off, he is exceptional. Best fighter I ever faced, without a shadow of a doubt.
"For sleight of hand and foot, he is just phenomenal - a really brilliant fighter - and a great fella [sic] as well, by the way.
"Secondly, do I think he is a genuine threat to the heavyweight division? Absolutely yes, that's the first thing.
"But do I think he can beat the big, big boys? I just don't think he can, mate. That's the only worry - the big, big boys.
"Don't get me wrong, Tyson Fury and AJ are just too big, mate; they are too big and dangerous and they will catch up with you in the end.
"But anyone around his size and frame - trust me, mate, he is a tough puzzle to solve."
These are legitimate concerns raised by Bellew. He knows first hand just how good Usyk is, and a boxer of his ability will always cause a stir in whatever division they find themselves in.
But the question is, how far can this take him in the heavyweight ranks? A lot of the questions surrounding Usyk may well be answered against Chisora.
The Brit will really pressurise Usyk and do his best to make it as uncomfortable as possible for him. The former unified champion has not faced anyone with the punching power of Chisora yet, so that is the most intriguing factor heading into this fight.
Usyk should have enough to his arsenal to beat Chisora, but if the Brit drags him into deep waters, it will be fascinating to see how he deals with it. If he passes this test with flying colours, we should not have to wait too long for him to face the likes of Joshua or Fury.