The 31-year-old Brit lost his three world heavyweight titles as his Ukrainian opponent outboxed him to claim a unanimous decision victory at the Tottenham Hotspur Stadium.
And Hearn, who has already confirmed that the second fight with Usyk will take place in the early part of next year, also insisted Joshua will look to alter things in his preparation for the rematch.
Speaking to iFL TV, Hearn said: “They’ll be big changes going into the next fight.
“It’s not just a case in the rematch of ‘right, from the first bell just steam into him mate and just let your hands go’. But there is an element of that.
“He will be looking to take Usyk’s head off in the next fight because he knows he can’t do it the other way. Not because he doesn’t have the ability, it’s just Usyk.”
When pressed on any changes to Joshua’s personnel in camp, Hearn then added: “That’s not something I get overly involved with but I think he’ll look at it and say, ‘where do I need to improve? What do I need to change to beat Usyk?’
“I’m sure there are things that he knows he has to change or thinks he has to change and he’ll make those changes because you have to be brutal and you have to be honest with yourself and say, ‘maybe I wasn’t doing that right, maybe this wasn’t right’.
“There’s always things when you lose – sometimes you get beaten by the better man – but when you underperform like he did there’s a reason for that. He has to find those reasons and make sure it doesn’t happen again.”
Joshua’s loss to Usyk was the second of his professional career following the defeat to Andy Ruiz Jr in June 2019.
Usyk’s victory also puts on hold a potential undisputed fight between Joshua and Tyson Fury, which looked set to take place this year before an arbitrator ruled that Deontay Wilder had the contractual right to a trilogy bout with Fury.
Wilder will look to avenge his defeat to Fury when the two heavyweights meet in Las Vegas on 9 October.
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