Anthony Joshua should sack his trainer, according to boxing icon Lennox Lewis.
The British boxer fell to a shock defeat to Andy Ruiz Jr, losing his unbeaten record as well as three world title belts.
Both Lewis and promoter Frank Warren believe the defeat could have been, in part, down to his coach, Rob McCracken.
"I say you can’t go to university with your third grade teacher," said Lewis.
"They won’t have the answers you need at that level. You need a professor by then."
Warren added to The Telegraph: "I’ve made my views clear about the trainer. Somebody’s got to be accountable for this. I don’t like the trainer at all.
“I think his job as an amateur where he gets the best fighters given to him, everything’s been done with them.
"What’s he doing, an amateur trainer, training Joshua for professional title fights? What sparring operations is he getting? Sparring with amateurs.”
Joshua first claimed the IBF heavyweight title in April 2016 by beating Charles Martin, before defeating Wladimir Klitschko for the WBA title a year later.
He then claimed the WBO belt after beating Joseph Parker in 2018.
But Warren remained sceptical of his feats with McCracken.
He added: “I say what I see. What I’ve seen all the way through it is an outstanding young prospect not improved, not improved at all. The world heavyweight championship was given to him on a plate by the worst heavyweight champion ever in Charles Martin.
"He then fought Wladimir Klitschko who had been taken to school 18 months earlier by Tyson Fury. Klitschko has always been safety first. He had Joshua on his backside, and if he had anything like Ruiz did, Klitschko would have stopped Joshua.
"Show me a world class fighter Joshua has fought other than that? Dillian Whyte? Whyte was in a life-and-death fight with Dereck Chisora, and Tyson Fury didn't just beat Chisora but destroyed him in their second fight.
"At the end of the day it’s about boxing. Joshua has done really well with the endorsements. But the world will now change for Joshua big time."
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