Deontay Wilder is the self-proclaimed "baddest heavyweight on the planet", but what is he like away from the media spotlight and what is it like to be a regular sparring partner of the destructive knockout artist.
Alonzo Butler, 38, nicknamed 'Big Zo', has trained alongside the American star for around ten years, sparring many rounds with 'The Bronze Bomber', and he knows all about the fearsome boxing style of the WBC heavyweight world champion.
With Wilder set to rematch Bermane Stiverne this Saturday night, live on Sky Sports, before pursuing a huge unification showdown with Anthony Joshua, Butler gives an insight into life away from the camera with the champion…
So you've been sparring Wilder, how did that come about?
Yes, I've been helping Deontay get ready for his fight with Stiverne and joined his camp about two weeks ago.
This isn't our first time sparring, no way, I'm the one who got Deontay ready for the Olympics all those years ago and I've been sparring him regularly ever since.
What's he like in the gym day to day?
For me, it's just a normal day's work, we've been doing this a hell of a long time now. We are like brothers, Deontay is a very down to earth man, very humble and respectful.
What are his main fighting strengths?
He has a brilliant jab, it's real hard, and he uses it to keep the distance before bringing that devastating right hand into play.
We all know about his power, he hits with a lot of venom. I would say he punches as hard as Oliver McCall if I had to compare it to anything I've faced before.
What about his defence?
Oh, his defence is much better, it's getting a lot harder to hit him now. He's fighting like a tall guy and keeping his distance really well.
So you've seen a lot of improvements in Wilder since you first met?
Definitely, when I look back he's got a whole lot better since the Audley Harrison fight and even when I see him now compared to the first Stiverne fight - he's better now than I've ever seen before.
Are you expecting him to stop Stiverne then?
He's looking sharper than ever, I believe he will get Stiverne out of there in four or five rounds. He's smarter and really knows what he is doing, the game is slowing down to him so it's getting easier.
A fight with Anthony Joshua is what everyone is talking about, how would that go?
If they fight, Joshua is gonna get tired and gas out by the fourth or fifth round. If he doesn't gas out, it will be a good fight, but if he does gas, Deontay stops him.
And yourself, will we see you here in the UK soon?
I'd love to get a chance to fight in the UK. The British fans love boxing, I see the 'AJ' fights and even smaller shows and the fighters get so much love and support - I want to be in that atmosphere.
I would love to take on Dillian Whyte, that's the one I fancy, but if not him, I'll take on anyone in the UK.
Watch Deontay Wilder defend his WBC world heavyweight title against Bermane Stiverne, live on Sky Sports, in the early hours of Sunday morning at 1am. Before that, Dmitry Bivol, Jamie McDonnell, Dereck Chisora and Scott Quigg box in Monte Carlo, live on Sky Sports from 7pm this Saturday.