Kubrat Pulev believes he can exploit Anthony Joshua’s weak mindset when the heavyweight rivals clash next month.
Pulev will challenge for the Brit’s three world titles in London on December 12, three years after pulling out of their first meeting due to injury.
And he insists he can follow in Andy Ruiz Jr’s footsteps and expose Joshua.
“I have been watching his fights carefully. He has a good style and he is a good specimen, but he has not shown any mental toughness,” he said.
“Yes, he has skills, but he hasn’t shown the mental strength. This is something from within, in the blood of a man, and he does not have it.
“Whatever mental toughness he’s got, I know I’m the harder person. This is the difference – my toughness will prevail.”
Joshua was dropped four times by Ruiz Jr last summer as he lost for the first time as a professional.
The Brit won his titles back six months later however when he outpointed the Mexican-American in their desert rematch.
But Pulev believes Joshua is still vulnerable and vowed to learn his own lesson from his sole defeat by Wladimir Klitschko.
“This is going to be a mind game and a chess game for as long as it lasts – a master chess game – but the only difference is the end is going to come like lightning,” he added.
“I can tell the fans that I will expose AJ again and prove they have been idolising the wrong guy. I will expose him to the world for a second time.