Terence Crawford and Jose Benavidez Jr started their big fight early when they clashed at Wednesday's media workout.
Crawford defends his WBO Welterweight Title against Benavidez in his hometown of Omaha, Nebraska on Saturday, live on BoxNation.
But the verbal blows were thrown when Crawford turned up while his unbeaten challenger was working out.
Crawford said: "It's (ill-feeling) been real since day one, since the fight has been announced. It ain't been nothing but real. I'm just going to go out there and shut him up. That's it. That's all.”
Benavidez, who has recovered from being shot in the leg two years ago, believes he is primed to shock adding: "It's time to show the world what I can do. I've been waiting for this my whole life.
"I am here. I am going to take over this city, and I am going to take his belt. I'm not scared. I don't see anything special in him. I don't know why everyone hypes him up so much," he added.
Much of the build-up has surrounded Crawford facing IBF king Errol Spence or WBA Super Champ Keith Thurman in a unification fight next year.
Crawford, who has won all 33 fights, knows he cannot write off his Arizona rival this weekend even if there has been little respect shown so far.
"I'm just gonna keep doing what I've been doing, and that's winning the fights and looking spectacular each and every fight. Everything else will fall into place.
"It's part of the game, but I'm not worried about that. They do their thing, and I'll do mine on Saturday. Once he feels them punches going upside his head, I don't even know if he's going to want to stand there next to me," warned 'Bud'.
On the same bill, rising star Shakur Stevenson now meets late sub Viorel Simion for the vacant WBC Continental Americans Featherweight belt.
Romanian Simion, 36, has won 21 of his 23 bouts with his only defeats coming against Lee Selby (2013) and Scott Quigg (2017).