Andy Ruiz Jr has cast doubt on a slimmed-down Anthony Joshua's ability to absorb a punch.
Joshua lost his three heavyweight world titles to Ruiz in June but has the chance to win them back on Saturday week.
He has noticeably lost muscle mass during his training camp for the clash in the Saudi Arabian desert. But Ruiz believes his rival may have made a mistake.
"I saw videos where he looked slimmer. I don't know if that's an advantage or a disadvantage," he told Sky Sports.
"I don't know if he will take the punches as well as he did when he weighed more."
Ruiz was criticised for his weight and body shape before he stopped Joshua four times and stopped him in New York.
The Mexican-American also expects to weigh less for the rematch but insists his performance will not be affected.
"Me? People are saying I lost too much weight, I won't be strong, he will move me around. I am losing eight pounds from what I weighed on June 1. I'll still be the same, I'll still be strong.
"AJ has always been in shape. He has always looked really good, really cut up."
Joshua has already arrived in Saudi Arabia where the purpose built 15,000-seat stadium has been completed.
The arena will be ripped down after the event as the country looks to bolster its profile as a sporting destination.
Upon arriving in the desert, Joshua said: "It's going to be an incredible night and I'm thrilled so many of my fans are going to be there, particularly from the UK.
"It'll definitely be a night people will tell their grandchildren they were at, one of those iconic evenings of boxing.
"Everyone from Saudi has been brilliant to work with."
