LONDON, England - Frazer Clarke was one of the few people in the world who tuned in to Oleksandr Usyk's Wembley Stadium demolition job on Daniel Dubois knowing how it feels to share the ring with both men.

And, although his crushing one-round defeat to Fabio Wardley last year pushed him to the back of the queue, the 33-year-old is convinced that a couple of strategic victories could move him back towards a shot at one of the four belts Usyk currently holds.

But 'Big Fraze' is as realistic as he is honest and laughed when he recalled his spars with the two combatants in last weekend's undisputed main event at England's national stadium.

Like Dubois, the man from Burton is a hulking 6ft 6in heavyweight with a well-schooled and educated boxing style so it was no surprise when Team Usyk came calling for sparring ahead of the rematch.

Unfortunately for Clarke, he could stay for only one day due to complications for his heavily pregnant partner back home. Thankfully, she made a full recovery as mother and newborn daughter are now doing fine but the concern at the time required a swift camp exit for Clarke.

"When I went over there my missus had a scare and it looked like the baby was going to come two weeks early," Clarke tells the Ring.

"So I was only there for a day and then I had to say 'sorry guys, I've got to get off because the baby looks like it's on its way'.

"It was all a bit crazy but I did manage to get one sparring session in with Usyk which I was over the moon with. I got to see the actual stuff, not the hype, I got to see what he's all about.

"He's a phenomenal character but also an athlete and boxer. At 38 years old he's as fit as they come, let me tell you.

"There were four of us brought in for sparring and in that session we all did three rounds each. But those three rounds honestly felt like six. I was the first one in but the pace he set from the first bell and then carried throughout the spar was something really impressive to watch."

Clarke's previous sparring partners read like a who's who of the heavyweight division. For example, only weeks after his bruising 12-round draw with Wardley in their initial fight last year, Clarke travelled to Germany to spar Agit Kabayel.

But this was his first experience of the two-time undisputed heavyweight champion and arguably one of history's very best in the division.

"He's just a very professional guy, Usyk,” Clarke adds. "He doesn't make mistakes and that's what struck me when I was watching the fight.

"People often say he has mesmerising footwork or mesmerising this and that but if you actually look at it, he does the basics. But he does the basics at a 15 out of 10 level."

It was no surprise for Clarke, therefore, when Usyk took Dubois out in such explosive fashion but he is also acutely aware of the game-changing power the Londoner possesses. He failed to get any of it off at Wembley, but he did once up at GB in his very first spar with Clarke.

"Let me tell you," Clarke says. "And I have no shame in this.

"I remember him coming to the gym - a big, quiet lad. It wasn't the same frame he has now, a little bit smaller but still just solid muscle.

"I remember getting in there, we are sparring and then it all just went slow motion. I remember it like it was yesterday. Bang. He hit me with this left hook and the next thing I know I was sat right on my backside.

"I sat there on my arse and thought 'oh my God'. I was gearing up for the Olympics in 2016, Joe Joyce was already a massive stumbling block and now they've brought this kid up here to put me on my arse as well.

"But we carried the spar on and had some really good work over the years, me and Dan. I always knew from that moment there that you can't step into the ring with Daniel Dubois underprepared because if you do he will put you to sleep.

"And that's what is so good about Usyk; his discipline. If in one of those exchanges where Daniel landed a big right hand on the glove, if Usyk is undisciplined and his hand is two inches lower, we are having a different conversation because Daniel's knocked him out cold.”

The defeat left 27-year-old Dubois on 22-3, 21 KOs and some have questioned whether we will ever see him return to the ring. His fellow British heavyweight Dave Allen, for instance, suggested it might be a good time to retire.

But Clarke said: "He's only 27, he's got ages left and I think he will be back 100 per cent. I do believe Daniel has been bred into it and I think this is all he knows."

The same could be said of Clarke, who has now been boxing for more than two decades having initially taken up the sport aged 11. It is why even the brutal nature of his defeat to Wardley, and the injury that came with it, was never going to make him walk away.

Instead, he returned to the ring with a first-round victory over Ebenezer Tetteh in April and now looks certain to get his third shot at the British heavyweight title in his next fight, although there is some confusion over who his opponent might be.

"If I look at where I'm at in my career I just think it's the natural step," says Clarke, now 9-1-1, 7 KOs.

"I'm not saying I'm above that level but I think that's where I've landed at this particular moment. I think I should be able to compete for the British title then we will see how I perform in that fight and then reassess.

"Only then will I know if I can make that big jump and get in with some of the big names because that is what winning the British title can do for you. You can go from British champion to boxing in Riyadh against a crazy name in a crazy fight.

"I know where I'm at to be honest but I also know that in this game, if I win a couple now I could be right back up there again. I could win the British next and then my next fight could put me in the top 10 - that's the reality of it.

"I've seen these top guys up close now. I've seen how Usyk trains and done many rounds with people like Daniel. If that is not good experience for someone like me trying to reach the top then I don't know what is."