The Croatian boxer will take on Dubois in a heavyweight bout in Saudi Arabia on June 1 and says he will end his career if he cannot repeat his triumph over the Brit who he defeated in sparring several years ago.

Hrgovic told IFL TV: "I don't know why he mentioned that sparring, because that sparring was not so good for him. He should be quiet about that.

"He said he changed – of course he changed. He was young at the time of sparring, but I was young as well. He has definitely improved, but you can never change your character, you can never change who you are as a man. I'm confident that I will repeat that sparring (result) on June 1."

The boxer added: "Of course (I would retire if I lose). How can I live with that? I think I'm the best. I worked hard 18 years in this sport like a maniac. So if I lose to Dubois, obviously I'm not as good as I think I am. So I would retire."

The IBF world title belt could be available for the fight but Hrgovic revealed that he could be forced to step in for Tyson Fury if the Gypsy King pulls out of his bout against Oleksandr Usyk.

He said: "My understanding is that I'm the mandatory challenger. Fury and Usyk fight on May 18 – after that fight, the winner should vacate the title. So me and Dubois should fight for the IBF belt.

"But in boxing, you never know – maybe May 18 doesn't happen again, and I need to jump in and smash Usyk. They told me I should be ready to jump in if something happens."