Anthony Joshua says breaking down Dominic Breazeale's mental strength is the secret to a successful world title defence on Saturday.
Joshua's IBF heavyweight belt is the prize at stake at the O2, the venue for Saturday's Sky Sports Box Office main event.
The fighters' physical attributes were laid bare for a huge Covent Garden crowd to see at Friday's weigh-in, Breazeale 11lbs heavier than the champion at 18st 3lbs.
But Joshua afterwards told Sky Sports News HQ the fight will be won and lost in their heads once the first bell goes.
"Dominic Breazeale is an articulate man," he said. "There's so much about the body - we train for weeks to get in shape - but he's got a good mindset. I need to break him right down, defeat him mentally and the rest will fall.
"I've got 24 hours to make every second, minute and hour count so I've got to rest up. It's a brilliant turnout here and that's all positive energy. I've got to take that away and let it all out on Saturday night."
Joshua is conceding height as well as weight and hopes the imbalance will provide an "opportunity to move around and pick my shots, to go on the back foot and use my boxing skill."
But Breazeale is promising "explosive fireworks" from the start, and the American told SSNHQ he expects Joshua's army of fans to switch sides before the night is out.
"This is Anthony's hometown and I've got to expect that," Breazeale said after he was booed at the weigh-in. "The fans are going to have his back, but after Saturday night they're all going to be my fans and I'm looking forward to it.
"In the end I'm going to knock out Anthony Joshua. That's what I came here to do."