Deontay Wilder warned he will show "no mercy" on a trimmer Luis Ortiz when they do battle in a heavyweight rematch at the MGM Grand on Saturday.

Ortiz weighed in at 236.5lbs in Las Vegas on Friday - five pounds slimmer than when they first fought in March last year - and Wilder tipped the scales at 219.5lbs.

Wilder knocked Ortiz out in the 10th round of their first bout in Brooklyn and the WBC world champion declared that history will repeat itself.

"This time he knows what it's going to be, he knows what happened the first time and what will happen the second time. He looked good though," said the American.

"On Saturday night, I will have no mercy for him when I'm ready to do what I do. We know what's coming but we don't know when it's coming. When it does, bang, goodnight.

"Don't blink, it's going to be an amazing fight."

Veteran Ortiz was in no mood to respond to the trash talk.

"Tomorrow is our night, I'm ready." said the 40-year-old Cuban.