I’m breaking boxing’s rule of secrecy… Daniel Dubois DID KO Anthony Joshua in sparring, with AJ out cold for 5 minutes

IT will be a surprise to most if Daniel Dubois should KO Anthony Joshua at Wembley on Saturday — but it would be the second time he has flattened him.

Among boxing’s many unwritten codes of conduct is whatever goes on in the gym stays in the gym.

Anthony Joshua and Daniel Dubois are set to face off at WembleyGetty

Joshua was knocked out by Dubois 10 years ago during a sparring sessionGetty

Dubois’ punch knocked Joshua out for five whole minutesGetty

But I’ve decided to break boxing’s rule of omerta and reveal what happened between Joshua and Dubois behind the closed doors of a Sheffield gym a decade ago.

Dubois, then a teenage amateur, was sent to Yorkshire to work with the far more experienced Joshua as part of his learning process and they sparred dozens of rounds together.

One day they were supposed to have a gentle sparring session and when they started there was no hint of the drama that was about to come.

Whether it was youthful exuberance or he meant to do it only Daniel knows, but out of nowhere he crashed a mighty left hook on Joshua’s chin and he was out cold.

Such was the power of the punch my informant, who must remain anonymous, assures me it took Joshua five minutes to recover from that stunning blow.

The horrified Joshua camp insisted those who had filmed the incident on their phones wiped them clean.

Though the story quickly circulated on the grapevine it was vehemently denied and put down to a malicious rumour.

It’s possible that memory will give Dubois, 27, an extra psychological boost when he defends his IBF world heavyweight title against Joshua in London.

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ANTHONY JOSHUA VS DANIEL DUBOIS: All the information you need ahead of huge world title fight at Wembley

I feel I have a vested interest in both men — SunSport readers were first made aware of their potential in this column.

It was 14 years ago when I sat on the ring apron with impressive 20-year-old Joshua at Finchley ABC shortly after he had won the ABA title.

Joshua told me he had turned down a £50,000 offer to turn pro as he wanted to compete at the London Olympics.

Dubois took a completely different course, forgoing the chance of Olympic gold in Tokyo and turning pro at 20 despite having just a few senior amateur contests.

AJ and Dubois are explosive punchers and likely to have what Nigel Benn would call “a tear-up”.

It could come down to the first one to land a blockbuster and that means Dubois has every chance of toppling the 3/10 favourite.

But Joshua has far more experience of the big occasion in giant stadiums — this will be his seventh open air fight in Britain.

Unless AJ gets careless and leaves his chin exposed, I expect he’s going to be much too powerful for Dubois.

And I will be surprised if he hasn’t finished the job by the fourth round.

Joshua vs Dubois fight predictions

THIS weekend Wembley will witness one of the biggest all-British fights of all-time.

But who will emerge victorious under the famous arch? Some of the biggest names in boxing have been having their say…

Oleksandr Usyk: “My favourite is Anthony Joshua but I am very bad at predictions. But I will predict Anthony Joshua.”

Dillian Whyte: “I just think that it’s one of those fights where it is a genuine 50/50 fight in my opinion.”

Joe Joyce: “I was initially edging with Joshua but I don’t know, Dubois is coming on.”

Frazer Clarke: “As heavy-handed as Dubois is and as good a fighter as he’s becoming, I still have to go for Joshua.”

Francis Ngannou: “Even though Joshua lost against Usyk twice and Dubois fought Usyk and almost knocked him down and almost won, I would still give this to Joshua.”

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