Deontay Wilder and Tyson Fury will not face off at Friday's weigh-in as organisers of their rematch move to prevent any possible on-stage clash.
Fury, 31, and WBC world heavyweight champion Wilder pushed one another at a news conference before their 2018 bout.
They did so again at a news conference on Wednesday, when organisers were left frustrated by the time it took for security to intervene.
The Nevada State Athletic Commission has now chosen to scrap the face off.
At Wednesday's news conference, Briton Fury and American Wilder, 34, pushed each other before interviews began. When they were asked to square up again after the media event, promoter Bob Arum shouted "no".
The pair are being tipped to achieve two million pay-per-view sales priced at $74.99 in the US.
As a result, the commission sanctioning the bout has acted with caution as any injury or incident that could lead to a postponement would see organisers lose out on millions of dollars.
"I think this is a big deal, a lot of people have invested in this fight, a lot of people will be here, a lot of flights and tickets sold," Wilder said. "They don't want anything to jeopardise this fight and I'm fine with the decision."
The fight has seen parallels drawn with iconic bouts of the past, including Lennox Lewis' fight with Mike Tyson in Memphis in 2002. On that occasion the former heavyweight world champions weighed in three hours apart in a bid to avoid a clash.
Wilder and Fury clashed at the main pre-fight press conference on Wednesday
Lewis is in Sin City as a television analyst and on Thursday, told BBC Radio 5 Live he believes Fury is taking a risk if he chases the early knockout he has promised.
Fury rose from the canvas in the ninth and 12th rounds when he drew with Wilder in Los Angeles 15 months ago and has threatened to move away from his usual evasive style.
"I believe he may go out and try to take Deontay on," Lewis told the 5 Live Boxing Podcast.
"You have to remember, he rose in the 12th round after being knocked down and attacked Deontay. He looked strong, maybe this may transcend into the next fight with him knowing 'I was strong last time, maybe I can take him out'.
"I have seen Deontay punch, he has that killer instinct and a right hand that comes from anywhere, so he [Tyson] is taking a chance."
Wilder, who has held the WBC title for over five years, has one of the most feared right hands in boxing history and has a 95% knockout ratio, the highest of any world heavyweight champion.
"If that's the only punch I have to worry about, that's the only punch that will not hit me," Lewis added when breaking the bout down for 5 Live.
"I've been in fights with guys with a great left hook. I've thought OK, I'll practice walking around with my right hand glued to my chin so the left hook can't get me.
"The first fight was filled with drama. Here we are seeing it again, excited, and we still don't know what's going to happen.
"It's the puncher or the boxer. If the boxer stays away from the puncher, the boxer wins. If the puncher gets through, he wins."
Fury and Wilder will weigh in at about 23:00 GMT on Friday, with thousands of fans set to attend at the MGM's Grand Garden Arena.