Joshua and Usyk are set to square off for a second time in Saudi Arabia on August 20 and Joyce will be watching with a keen eye.
The Juggernaut admitted that he thinks his fellow Brit hasn’t been the same since his devastating knockout loss to Andy Ruiz Jr in 2019.
And he also claimed that Joshua stopped responding to his text messages a while ago in the wake of that defeat.
Joyce told The Sun: “I’ve known Joshua for a long time and know he is a good guy and comes from a good place.
“For a long while, he looked unbeatable and then it all came crashing down with the Andy Ruiz loss — and that must have been hard to come back from.
“He won the rematch on the back foot and looked scared to get hit. He has a lot to prove.
“He has never reached out to me. I used to have his number and we’d catch up occasionally.
“But after the Ruiz loss, I tried to send him a nice message and I think he might have changed his number — or thrown the phone in the sea.
“I still want to see him fight Fury but I’d also like a chance to fight him, so, hopefully, he doesn’t retire before that.”
Joyce also believes that Joshua should go back to the basics against Usyk to stand any chance of winning.
He added: “AJ has gone a bit odd more recently.
“He’s a bit of an odd guy — he used to be different.
“In sparring sometimes, he used to come toe-to-toe, tache-to-tache and swing bombs.
“It used to be very exciting and I used to really like sparring with him like that.
“But, all of a sudden, he started working on his technique and using his footwork, being out of range and stuff.
“He switched up his style a little bit and didn’t go gung-ho.”
Much has been made of Joshua’s decision to replace his former trainer Rob McCracken with renowned coach Robert Garcia.
But Joyce doesn’t think it will be too much of a problem so long as he takes everything new onboard.
He continued: “Changing your trainer can be hard but it depends on how you are as a person.
“If Joshua can absorb all the new information and tactics then it could be fine.
“But it also can take time to adapt and incorporate into your sparring and fighting.
“I really hope he can win the rematch for British fans and for British boxing.
“Joshua has a chance. He showed how he can turn it around with the Ruiz rematch when he came in with some different tactics.
“He was competitive in the first Usyk fight and he has good power.
“So, if he can take it to Usyk like he should have done in that first fight, he has a puncher’s chance.”