Oleksandr Usyk sparring to fight Tyson FuryCredit: Instagram @nursultan___amanzholov

It will come just four months after Fury, 35, was dropped by ex-UFC champion Francis Ngannou, 37, in his controversial points victory.

The crossover clash was meant to be a routine rout but it turned out to almost be the mother of all banana skins.

Fury’s dad John spoke out to say his son’s training camp is a “circus” and he fears it will carry on over to the Usyk unification.

And the worrying reveal has ex-cruiserweight champion Nelson believing the historic title fight could face a further postponement.

He told ProBoxingFans: “If he doesn’t fight February 17 then we have a problem.

“Because if his dad’s saying it now, it gives you a sense there might be a delay, they might want more time.

“I wouldn’t be surprised if they wanted to push it down the line a bit.”

Fury’s dad John was not happy with the preparation to fight Ngannou – and he worries that there has been no change.

He told Seconds Out: “I never said my son was in decline because he’s not.

“It’s the people around him who ain’t up to much. His training’s in decline and his camp’s in a bigger decline. It’s not a camp, it’s a circus.”

“I saw him in the gym in Saudi, watched him spar three or four rounds with a couple of kids – I knew then it was gonna be a hard night’s work.

“I thought, ‘What have you been doing?’ I was alarmed, I still am.

“Unless you’re gonna get the eye of the tiger back and go back to the old ways and get the hunger back – sweat, blood, s*** and tears

“Because Usyk’s doing that – sweat, blood, s*** and tears. And he’s got disciplined, professional, great people around him, and I don’t think Tyson has that. I really don’t.”

Fury was recently slammed by Usyk’s team for holidaying in Saudi while the Ukrainian is busy sparring 6ft 10in powerhouses.

And asked if he fears his son could suffer defeat for the first time, John admitted: “Absolutely, if he doesn’t make any adjustments, it well could be.”

Fury enjoyed parasailing in the Middle East with his wife Paris and their seven kids.

But he is now back in his Morecambe training base with head coach Sugarhill Steward.

And he has also called on the help of unbeaten southpaw Thomas Carty, jobbed with replicating Usyk in sparring.

Johnny Nelson fears Fury vs Usyk will be postponed againCredit: Action Images – Reuters