Paddy Pimblett insisted that the crowd's reaction irked Justin Gaethje when they went face-to-face for the final time before their UFC 324 fight.
Pimblett (23-3) and Gaethje (26-5) will vie for the UFC interim lightweight championship on Saturday night in Las Vegas.
It is a chance for Liverpool's Pimblett to become the fourth Brit to hold a variation of UFC gold, whereas veteran Gaethje has conceded this will be his last chance to become a champion unless he prevails.
Pimblett and Gaethje were both inside the 155-pound limit at Friday's weigh-in before exchanging words.
A grinning Pimblett asked when they are close quarters: "How did the weight cut go?"
Gaethje replied: "Great."
Pimblett smiled and said: "It doesn't look like it!"
Pimblett later insisted that his rival was bemused by an unexpected reaction from the American crowd.
"I am properly enjoying it, I will take over this [arena] when I walk out," Pimblett told TNT Sports. "Everyone will be singing: 'Oh, Paddy the Baddy!'
"I think that's what got under Justin's skin. He's thinking: 'I am American in a main-event in Vegas, why is everyone supporting him?'
"Everyone was cheering for me, and signing my name.
"When Sean O'Malley was having a back-and-forth with Song Yadong, everyone was singing 'USA.'
"He's thinking: 'Why aren't they doing this when I have a back-and-forth with Paddy?'
"I think it's in his head already. He is thinking: 'I am normally the fan favourite.'
"Well, this time you're not, son."
Pimblett is best-known for his submission skills but has repeatedly insisted he could knock Gaethje out on Saturday night.
He pinpointed his pathway to victory: "Keeping my distance, keeping my range. When he tries to cause chaos, either catch him with a shot and knock him out, or getting a takedown, a scramble, then choking him out."
Gaethje had dismissed Pimblett's grappling by insisting his opponent isn't the mighty Khabib Nurmagomedov.
"I know I'm not, and Khabib is not me," Pimblett reacted. "I'm nothing like Khabib, I know. Apart from when I'm on top and I smother.
"If I get on top of Gaethje it will be over within two minutes. I couldn't get over how long his neck was..."