Anthony Joshua defends his WBA, WBO and IBF world heavyweight titles at Madison Square Garden in New York, this weekend.
His clash with Ruiz Jr will be his first fight in America, after spending the entirety of his 22-fight career so far in the United Kingdom.
The opportunity was offered to Luis Ortiz, who reportedly asked for too much money, before the fight fell to Mexican Ruiz Jr, who grabbed the chance with both hands.
And Hearn told iFL TV that he was surprised to see how excited the 29-year-old was about the fight.
“Andy Ruiz is on another planet, he is so fearless that he doesn’t realise what’s about to happen on Saturday, he’s just excited,” Hearn told iFL TV.
Ruiz is the overwhelming underdog ahead of Saturday night, with many fans predicting he will be stopped early in the fight.
However, with the chance to become Mexico’s first-ever heavyweight world champion, ‘The Destroyer’ revealed he is planning a knockout win of his own.
Speaking to SecondsOut, he said: “A lot of people underestimate me, like I said, the way I look, my appearance, but as soon as they see me throw punches, I’m going to pull out the upset.
