It's no secret that Anthony Joshua has been knocked down in sparring before.In the lead up to his unification bout with Joseph Parker on March 31, promoter David Higgins goaded Joshua with a number of tales from the gym. Eventually, it prompted Joshua to concede that David Price had once sent him to the canvas during his amateur days.He didn't, however, admit to a long standing rumour that he had been previously knocked down by Daniel Dubois.The 20-year-old is only seven fights deep into his professional career, but has impressed many within the British boxing scene.And the reports that he had flattened Joshua during sparring resurfaced this week when Frazer Clarke - fresh from securing gold at the Commonwealth Games - refuted the claim entirely.

Clarke rubbished the rumours

On Sky Sports' Toe-To-Toe, Clarke stated: "I am sure I am at 99 per cent of the spars and it has hit him flush and has probably shook him up a bit, but the way they make out that he put him down on his backside, it just never happened.

"I don't think it was Daniel, it's the people around him. Daniel is a nice kid and he probably admitted he shook Joshua up a bit in sparring and someone has made more of a story of it.

"I can honestly say if it was true, Joshua would turn round and say 'yeah, it happened, it was true', but he hasn't."

Warren responds on Twitter

Well, that's that then - or is it?

Dubois' promoter Frank Warren picked up on the quotes on Thursday and simply couldn't let them slip.

Both he and Dubois himself have always maintained that Joshua hit the canvas and Warren took it upon himself to tweet a response. To say it doesn't look good for Clarke's claim would be putting things mildly.

Take a look at Warren's response below:

Warren isn't happy.

The 66-year-old is notoriously frosty when it comes to Joshua - the prize asset of rival promoter Eddie Hearn.

Dubois is Warren's equivalent prospect in the heavyweight division and he'll be hoping his fighter will become a world champion of his own in the future.

So, it's natural that Warren would defend his fighter but it seems the flimsiness of Clarke's claims suggest he's exactly right, regardless of his own allegiances.

Ultimately, though, fighters can only take so much from sparring and it isn't the first time Joshua has been dropped.

That's not to say that fight fans won't want to see the two Brits slog it out in the future, however. Besides, the evidence is adding up to suggest Dubois has the power to give AJ some serious problems.

Do you think Dubois is a future world champion? Have your say in the comments section below.