Johnathon Banks, who at the time was the head trainer for Wladimir Klitschko, reflected back to April 29, 2017 - when his boxer collided with Anthony Joshua in a heavyweight unification, before a crowd of 90,000 fans at Wembley Stadium in London.

In the sixth round of that bout, Klitschko dropped Joshua in sensational fashion. He had the British star in serious trouble - but he was unable to finish him off.

"I said: 'Wladimir, you've got to finish this guy,'" Banks 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."

Klitschko's older brother, Vitali Klitschko, was also working the corner that night and blamed himself for the loss.

He told Wladimir to take his time, which in turn may have let Joshua off the hook.

"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]," Vitali said.

"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."

Banks went bonkers when he realized what Vitali had instructed.

"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," Banks said.

"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."

Joshua was able to recover as the fight played out, and stopped Klitschko in the eleventh round.

That contest was the final bout of Klitschko's career. While he initially exercised a rematch clause, he ultimately passed on the opportunity and announced his retirement.

Banks was very proud of his boxer's last in-ring performance.

"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," Banks said.

"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 movie - 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."