Sky Sports commentator Johnny Nelson says he saw Oleksandr Usyk give former heavyweight world champion Wladimir Klitschko a lot of problems during preparations for Klitschko's November 2015 fight against Tyson Fury.
Nelson also believes that Usyk has the potential to move up to heavyweight and challenge some of the bigger fighters such as Anthony Joshua and Deontay Wilder for their world titles.
Nelson told BehindTheGloves: “I rate Usyk. When I saw him sparring with Wladimir when Wladimir was preparing for Tyson Fury, I said ‘who is that guy? Who is he?'
“I had no idea, but I know there was something special about him.
"He did one round with Wladimir, and Wladimir slung him out and said, ‘get out, not while the press is here.’ He was making it hard for Wladimir. He was like bossing Wladimir. ‘Get him out. Get somebody else in.'
”I think he’s the one guy that will unify the cruiserweight division. I think he’s the one guy that can move up to heavyweight and win a world heavyweight title, and he’s still nowhere near the finished article. He’s still learning.”
Usyk will fight in may against Russia's Murat Gassiev in the World Boxing Super Series final in a unification fight with all four titles on the line and Nelson fancies the Ukrainian's chances.
"In his last fight, he was a little apprehensive, and then he realized, ‘I’m the boss here'. I think it’s a point’s win if not a late stoppage for Usyk. I think Usyk is a slickster. He’s a good boxer and a good fighter."
Usyk is certainly a precocious talent having taken fewer fights to become the world cruiserweight champion than Evander Holyfield, who famously stepped up weight divisions for fights against Mike Tyson and James Douglas.
Ukrainian Usyk has talked up his chances in the heavyweight division, telling Sky Sports: "I will move up to heavyweight and show them all how good I am.
"I think you can see yourself, I will fight him [Joshua]. Not yet though. But it is a question everybody keeps asking me, so once we go face to face, we will find out. It will be good."