Joshua (24-1, 22 KOs) has stopped all but two of his opponents and is the favourite against Usyk, who struggled against Dereck Chisora in his last fight in October at the SSE Arena in London.
But the former undisputed cruiserweight champion is undefeated with 13 knockouts in 18 wins and will pose a serious threat to the 6 ft 6 in Joshua, who recently told reporters he is looking forward to putting on a show at the Tottenham Hotspur Stadium in September.
And Hunter has also advised Joshua not to underestimate Usyk, having been on the receiving end of a lopsided unanimous decision to the 34-year-old Ukrainian fighter in April 2017.
“I don’t think Anthony Joshua beats Usyk unless he knocks him out,” Hunter said to iFL TV. “This is heavyweight boxing, so there’s always going to be knockouts.
“[Usyk] is strong enough and he’s an Olympian and all that. He has the accolades and attributes to do so.”
Hunter went on to say that he reckons Usyk’s technical ability could prove to be too much for Joshua.
“I just think Usyk is a little bit too fine-tuned for him,” he added. “People are always going back on the Chisora fight because he didn’t look so good.
“But I think that was more of a ‘styles make fights’ type of thing. It’s in his favour to box somebody like Anthony Joshua, in my opinion.
“You have to hit Usyk with something very sneaky when you’re that tall and that dynamic with Usyk and Anthony.”
He continued: “We know Anthony Joshua’s sneaky move is the uppercut, but that’s going to be a very rare punch to hit Usyk with.
“We know that Usyk is very defensive-minded and he’s not there to engage. He’s there to get the points and win.
“So it’s going to be a very difficult feat and challenge for Anthony Joshua.”