Rob McCracken has rubbished claims Anthony Joshua has a glass chin ahead of Saturday’s unification showdown with Joseph Parker, and claimed that few other boxers would have been unable to survive the Wladimir Klitschko onslaught in their title fight last year.

Parker’s camp have made repeated reference to Joshua’s inability to take a punch, even christening him ‘Glass Jaw Joshua’ at a controversial press conference earlier this year.

Much of the logic behind that line of attack seems to stem from Joshua’s performance against Klitschko – when he was knocked to the canvas in the sixth round before battling back to land a famous victory – but his trainer McCracken has argued the shots his man weathered would have knocked out most challengers.

Anthony Joshua's open workout in pictures Show all 38 1 /38 Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua takes a break during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media Workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media Workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua trains during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua looks on whilst stretching during a media workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua stretches during a media Workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images Anthony Joshua's open workout in pictures Anthony Joshua's open workout in pictures SHEFFIELD, ENGLAND - MARCH 21: Anthony Joshua greets Robbie Savage during a media Workout at the English Institute of Sport on March 21, 2018 in Sheffield, England. (Photo by Alex Livesey/Getty Images) Getty Images

"Here's the thing just so we can clear it up,” McCracken says. “People say 'oh, he blows'. He got hit with about 30 sledgehammers in rounds five and six against Klitschko.

“It's like being in a car crash. Klitschko hit him on the chin with about six left hooks, clean. Normally he knocks everyone out with those shots.

"So he's sat on his stool and he said 'I just need a round off here to get myself together'. That's how he thinks. There was no thought of this is going wrong. He thought he would get a round in, calm it down a bit and then he would sort it out.

"That's the conversation with him on the stool at the end of round five. He knew he had a terrible round, but he had a strategy to have a breather, and get his way back into it.

McCracken has trained Joshua since the end of 2016 (Getty)

"Klitschko is a phenomenal fighter and a phenomenal puncher. Klitschko was motivated to do that and a few of his left hooks would put you to sleep.

"For him to weather the storm, learn from it and to come back into the fight, was quite something."

McCracken believes Joshua is still not yet at his best (Getty)

After defeating Klitschko, Joshua accepted a fight with mandatory challenger Kubrat Pulev, only for the Bulgarian to pull out with a shoulder injury 11 days before the fight.

The veteran Cameroonian-French heavyweight Carlos Takam was brought in as a late replacement, but Joshua appeared to struggle in the fight, suffering an early nose injury before winning by way of a somewhat fortuitous stoppage.

Of the Takam fight, McCracken said: "It was a strange one. All the way through training, he finished up after training about 17st 9lb or 10lb. So I just presumed he'd come in at 17st 9lb or 10lb for the fight.

“But it was just the week of the fight when you ease off a bit he probably ate a couple of meals more than he should have and it was a 6lb difference.

Joshua defends his WBA and IBF heavyweight titles against WBO champion Parker (Getty)

“It was just taking it easy a bit too much so we'll be a bit tighter and more disciplined the week of the fight now. We should see him coming in a bit lighter.

"He's a massive bloke and his weight can sometimes be misleading but I just think as long as he feels good and he's sharp in the spars and he's doing 12 rounds without too much difficulty, that tells me he is where he should be.

“But you are damned if you do and damned if you don't because he is such a huge bloke, it is easy for him to put three, four or five pounds on in a meal. He is a giant.”

“He was late to the sport so that means he is not at his best yet,” McCracken said.

Parker, like Joshua, is also unbeaten (Getty)

Joshua ultimately prevailed and will be in line to fight for all four belts if he manages to defeat Parker on Saturday night.

A fight with WBC belt holder Deontay Wilder is already in the works while Tyson Fury also awaits somewhere along the line, and McCracken is confident that a hungry Joshua will only get better.

“It's funny with boxers – you go through the start, the middle and the end. He's still somewhere in the middle where he totally enjoys it and it's an adventure for him and exciting for him. The middle of your career is the best bit because you are just starting to realise you are not bad at it.