The 60 seconds of chaos after round six is the moment that Wladimir Klitschko’s team wish they could “rewind and do again”.
On April 29 2017 Joshua brilliantly came from behind to win the world heavyweight title fight at Wembley Stadium but there is still regret in the voices of Klitschko's corner-men that they didn't take advantage when in the ascendancy.
Vitali Klitschko publicly took the blame for his instruction to his younger brother to stay cautious and patient. In the previous round, Wladimir had knocked Joshua down and put him on the verge of defeat. So why did Vitali say that? Is he just covering for his brother? What is the truth?
"I said: 'Wladimir, you've got to finish this guy,'" Johnathon Banks, the head trainer, exclusively told Sky Sports.
"'No more boxing. Go get him! He's still hurt. You've got to finish him!'
"I believe he agreed but he didn't see what I saw. He saw someone still able to let their hands go."
Joshua had scored the fight's first knock-down in the fifth round but Klitschko recovered quickly. In the sixth Klitschko landed a thunderbolt of a right hand which sent Joshua to the canvas for the first time in his career. When Joshua rose, he was shaky and saved by the bell.
Surely this was the time for Klitschko to pour forwards and gamble?
Vitali, also in his brother's corner, had since admitted: "When Wladimir almost knocked Joshua out, I gave him the wrong advice. I was positive that Joshua, with his huge muscle mass, would not be able to last [the distance].
"I advised Wladimir not to rush anything. I had hoped that after the seventh, the eighth round... Joshua would really slow down. Now I think that maybe it was a mistake, maybe it was necessary to finish him off sooner."
Is it possible that the noble Vitali was just attracting blame to take the heat off his brother?
"Wladimir and Vitali speak in their native language so I didn't pick that up," cut-man Jacob 'Stitch' Duran told Sky Sports.
"I wish we could rewind and do that again."
But Banks, the American head trainer, told Sky Sports: "I understood Vitali say that in Russian. I jumped up! The security guards told me to sit down but I was shouting: 'Finish him, finish him!'
"I knew Vitali's voice would reign supreme over mine. I tried my best to override."
Sure enough, Klitschko didn't pull the trigger. Joshua bravely recovered and pulled off a spectacular comeback stoppage in the 11th round.
"If Wladimir had five percent more energy he would have finished the fight," 'Stitch' Duran regrets. "Joshua was one shot away from being knocked out."
Banks has never questioned his instructions being overruled by Vitali: "No, it makes no sense to bring it up. I've got brothers too and we're very close. If someone questions my brother, my initial thought is to defend my brother. I accept it and we move on.
"You've got to understand that to Vitali, it wasn't a mistake. His job is to protect his little brother. His emotion clouded the business.
"A lot of fathers who are trainers for their sons either stop the fight too early or too late.
"Someone unrelated? My job is also to protect but the emotion is different."
Wladimir Klitschko, once the world heavyweight champion for nearly a decade, retired after his stunning efforts at Wembley helped to catapult Joshua onto a higher level.
Banks recalled: "If I were in Joe Frazier's corner for the Thrilla in Manila would I be upset that we lost? Or enthused to be a part of such a historic event?
"I loved how Wladimir fought. He performed better in that fight than most people thought he had in his entire career.
"A lot of questions from his reign on top were only answered in that fight. He answered questions from critics dating back to 2004.
"Like The Gladiator move - you win the crowd, you win your freedom. Wladimir's lock and key was that he never went through [difficulty]. If you knocked him down, it was over - that was his chain.
"But he answered that question and gained his freedom.
"We lost the fight but, I believe, we won the war."
Watch The Boxing Show featuring Eddie Hearn and Barry Hearn at 2pm Friday on Sky Sports News.