The British superstar will rematch the Ukrainian in Saudi Arabia on August 20.
Joshua’s second meeting with Ukraine’s unified heavyweight world champion will see him bid to avenge the second loss of his professional career, which he suffered at the Tottenham Hotspur Stadium last September.
AJ has replaced former trainer Rob McCracken with new coach Robert Garcia in preparation for arguably the most important fight of his career, of which many argue he will be remembered for for the rest of eternity.
But Froch doesn’t believe he has made the right decision as he insists he should have stuck with McCracken instead.
“He’s made some big changes, AJ,” Froch told Betfred.
“He’s changed his coach which I’m against because I’m biased because I was with Rob McCracken for my entire career.
“I lost two fights and stuck with him and I wouldn’t blame Rob McCracken for that. AJ stuck something on Rob McCracken’s shoulders and thought ‘ok I need a change’. Sometimes a change is good and hopefully this change for AJ will allow him to get his mind back.
“He’s got all the bigger physical attributes. He’s bigger, he’s taller, heavier, stronger, punches harder and if he leans on his opponent then it will be hard work for Usyk. I was quite a nervous amateur and if your mind isn’t right and you don’t believe in yourself then you’ve got a whole mountain to climb.
“When you’re negative and you feel like you can’t beat somebody then it’s very difficult to start beating them. I think Anthony Joshua hasn’t had belief ever since the Andy Ruiz loss.”
The Englishman won 33 out of his 35 fights in total, 24 by knockout.
The 44-year-old also sensationally claimed that he has heard that Joshua has been taking it easy during sparring, and went on to say that he needs to take a good long look at himself and those around him.
He added: “I think Anthony Joshua needs a brain transplant to beat Oleksandr Usyk.
“He’s got all the physical attributes but I don’t think he can beat him. It’s nothing against AJ but Usyk is that good, he’s brilliant. Look at his amateur career, look at his undisputed reign at cruiserweight and then look at what he did after that.
“He stepped up and dipped his toe in it against Derek Chisora and then he did what he did against AJ.
“For AJ to win this fight then he has to be totally on his A game, thoroughly believe in himself, which I don’t believe he does and then wipe out his team that deals with all his sponsorships, which are on him for endorsements and the whole business side.
“I don’t think he’s putting the work in and I know he’s not putting the work in when he’s sparring. You’ve got to be a fighter, a boxer and you’ve got to do the fundamentals. I used to do a 12 month training camp and I never cut corners, ever.
“If he can do everything right and believe in himself then he may be able to get the win, but you have to say that he’s a massive underdog.”