Andy Ruiz Jr believes that he has identified Anthony Joshua’s weaknesses and will show him "no respect" in their world heavyweight title fight.
Joshua defends the IBF, WBA and WBO belts in his US debut on June 1, live on Sky Sports Box Office, but challenger Ruiz Jr plans to "take advantage" of his opportunity to cause an upset.
AJ has a style which will make me look impressive. Yes, he's strong and big. But my style will take away his advantages.
"There are weaknesses," Ruiz Jr told Sky Sports. "He is the best right now because he has the belts. But the guys he has fought? I've sparred with them and they wouldn't want to fight with me.
"AJ has a style which will make me look impressive. Yes, he's strong and big. But my style will take away his advantages.
"This is business. I have nothing bad to say about AJ. I am the challenger and he is the champion.
"There is respect between me and him - but inside the ring there will be no respect and I will try to win and knock him out."
Joshua is aiming to remain unbeaten in a 23rd fight, and an eighth world title fight, and has put together a string of victories that includes Dillian Whyte, Wladimir Klitschko, Joseph Parker and Alexander Povetkin.
But Ruiz Jr said: "Carlos Takam, Dillian Whyte? I thought: 'I can do a lot better than those guys'.
"I'm an exciting fighter. People look at me and say: 'he's slow, he will get tired'. But I'm a combination fighter.
"I move, I throw punches, I go in to knock out my opponents.
"Everybody that fights Joshua has fought scared - they move around and try not to get hit. But I'm not scared of getting hit. I'm here to get hit, and hit back.
"People like watching me fight because I'm not scared and I bring a fight."
Ruiz Jr has lost just once in 33 fights - he was beaten on points by Parker in 2016 with the WBO title at stake.
"I shocked Joseph Parker. I'm pretty sure he didn't think it would that hard. He thought it would be easy," Ruiz Jr said.
"This chubby kid? He thought he would box me around. But when he moved, I moved. When he punched, I punched. I really thought I won that fight."
Ruiz Jr beat Alexander Dimitrenko on April 20 so, although he challenges Joshua as a replacement for Jarrell Miller, he has benefitted from an extensive training camp.
He warned: "I've never been knocked out. I'm still young, 29, I've never been hurt and I've never been in a big war. This is the hardest fight of my career but I know I will pull off an upset.
"I believe in my heart that we can win, and we are going to win. It will be one of the biggest upsets in the world. I can be the first one to stop him.
"In America, you have to have a dream, and have the heart to pursue it. I am a family man and a nice guy but, inside the ring, I am an animal.
"AJ, get ready, get prepared. Don't underestimate or overlook me. I know I'm chubby and short but I'm as fast as lightning!"
Watch Anthony Joshua vs Andy Ruiz Jr at Madison Square Garden, New York, on Saturday, live on Sky Sports Box Office, from 10pm. Book it via your Sky remote or book it online here.
Even if you aren't a Sky TV subscriber you can book and watch it here.