Sparring sessions in boxing have always been a fertile source of rumour and intrigue as the reality of what goes on behind closed doors often remains shrouded in mystery.

The latest revelations from the sparring session from a few years ago between a then fit and firing David Haye and promising newcomer Deontay Wilder have been fascinating.

While a video released at the time of their encounter in 2013 seemed to show the Englishman Haye in the ascendant, dominating his inexperienced opponent with his speed and power, a witness to the session offered a more comprehensive view on proceedings.

Dave Coldwell a former team member of the Haye camp but now working with his fierce rival Tony Bellew was very impressed with how the current WBC champ Wilder looked after himself in the spar with Haye, when asked about the prospect of the American facing off against Anthony Joshua next year.

“I would say that Wilder is a slight favorite," Coldwell told FightHype.

"I don’t buy into it that AJ (Anthony Joshua) is the favorite because I’ve seen Wilder in sparring taking licks. We had Wilder over (to the UK) when he as a young kid sparring David Haye.

"I’ve seen David Haye detonate bombs on Deontay Wilder’s chin and him (Wilder) just coming back saying – lovely! Lovely! And coming straight back and winging them (punches) straight back! He’s (Wilder) tough. He’s a lot tougher than he looks.”

This note of caution from such a respected trainer might come as a surprise to many British boxing fans convinced that AJ's power would be too much for the American to handle. Unbeaten in 39 fights and boasting a 97 percent knockout ratio, though, it is clear that Wilder is not to be underestimated.

The WBC champion is currently preparing for a bout with dangerous Cuban Luis Ortiz in March but has already got his eyes set on a unification showdown with Joshua later in 2018, a fight that boxing fans all over the world want to see.