Anthony Joshua insists he will not make the mistake of underestimating stand-in opponent Andy Ruiz Jr.
Londoner Joshua makes his US debut when he defends his WBA, IBF and WBO world heavyweight titles at Madison Square Garden on June 1.
Ruiz Jr, nicknamed 'The Destroyer', was drafted in as an emergency replacement after an "adverse finding" was found in a drug-testing sample of original opponent Jarrell Miller.
Undefeated Joshua, 29, is eager to deliver a statement victory in America in the wake of rival WBC champion Deontay Wilder's stunning first-round knockout of Dominic Breazeale on Saturday.
Ruiz Jr, also 29, has a record of 32 wins and one defeat and is known for his speed in the ring.
The Mexican-American fighter's sole loss came in a WBO title challenge against Joseph Parker in 2016, the same opponent Joshua subsequently beat over 12 rounds last year.
Speaking from his training HQ in Miami, Joshua said: "It's not about what you look like. It's a craft, a skill. What's in your heart and your head matters in the end.
“Andy has shown he has all that. He can fight and box. That’s what matters. I think Andy is a great challenger and will bring it on June 1.
“All I’ve heard is ‘AJ will smash him in one round’. From the outside, they think that anyone can box. So how is the guy that doesn't look like a fighter able to box? I always say that if you put 10 bodybuilders in the ring, not one of them could fight for a regional title in boxing.
"Take me out of my body but keep the same attributes and height, same jab, same chin, same heart and same mind and I'd still get to the same position I am in because it's what is within you that makes a champion.
"It's your genetics. And his genetics are the same - and he took the fight. He's keen, he's game and you cannot knock him. He can fight and he's got fast hands. He gave a world champion in Joseph Parker lots of problems.
"Andy is championship level for sure, and I have not underestimated him one bit.”
