Heavyweight also talked out on the sparring between AJ and Dubois.

DANIEL DUBOIS left Frazer Clarke on his backside and startled during sparring, serving as a strong message to Anthony Joshua.

Joshua is set to face Dubois in a Wembley homecoming bout in September.

Anthony Joshua with Frazer Clarke and Daniel Dubois.

However, it will not be their first time sharing the ring after dozens of sparring sessions at Team GB’s Sheffield headquarters.

Clarke, an unbeaten fighter, was also involved in the practices, admitting Dubois had even dropped him.

He told SecondsOut: “I have no shame in admitting it; Daniel Dubois put me on my a**e with a left hook years ago. And he was young.

“I remember thinking, ‘Oh my God, this f***ing kid is something else.’ Obviously, he got back up and continued sparring, which is common in our division.

“But yeah, I’ve been on the side of the ring where these two have really had good exchanges and stuff.”

Rumors circulated for years that a teenage Dubois had also stunned AJ.

Despite Dubois’ impressive victory over Filip Hrgovic, Clarke remained tight-lipped about the conjecture and backed Joshua as the favourite in the fight.

He stated, “Anthony was always that little bit ahead, but father time happens, and Daniel has matured and grown as a fighter, which makes the fight more interesting.”

How AJ punched his way to the top

ANTHONY JOSHUA punched his way to the top of the world before being knocked off his perch.

From humble origins in Watford to Olympic hero, the boxer has made a heavyweight impact in and out of the ring.

Eddie Hearn claims a collision with rival Tyson Fury could be worth a whopping £200million.

The pair’s bitter feud saw them refuse to say a word to each other as they met Cristiano Ronaldo in Saudi Arabia.

Joshua has already hinted at when he will hang up his gloves.

And he revealed why his son will NEVER be allowed to box. despite amassing a £215m empire thanks to the sweet science.

AJ enjoys a lavish lifestyle including private jets and a £350k watch.

His career and sponsorship deals have seen him swap his council estate upbringing for a luxury car collection.

London hairdresser Kika Osunde is believed to have swept the KO king off his feet.

But Joshua still lives with his mum Yeta when he is not on the road.

“I still have AJ as a favourite just because of the experience and I feel like if Daniel took the same 30 shots off AJ as he did off Hrgovic we’d be having a different conversation right now.

“He’ll have to tighten up in his defences but him and the team are not naive they’ll know that but he’s shown a different side to him. I look forward to it.”

Clarke, 32, is coming off a fight of the year contender against British champion Fabio Wardley, 29, which ended a draw with rematch talks underway.

Meanwhile, Dubois, 26, stopped Hrgovic, 32, in Saudi Arabia to claim the IBF “interim” belt.

Oleksandr Usyk, 37, stills holds the full world title after victory over Tyson Fury, 35, in their undisputed decider in May.

But due to their pencilled in rematch in December 21, he could be stripped of the IBF belt due to being unable to fight challenger Dubois.

So promoters hope Joshua, 34, can face Dubois for the title at Wembley.