Promoter Eddie Hearn has described November's Jake Paul v Mike Tyson headline bout in Texas as "dangerous, irresponsible and disrespectful to boxing".
Former heavyweight world champion Tyson, 58, has not fought professionally since 2005, while YouTuber-turned-boxer Paul, 27, has won 10 of his 11 professional bouts.
Hearn will attend the event at AT&T Stadium to support Katie Taylor in her rematch with Amanda Serrano, but claims he will leave before the main event.
"The reality is that 20 years ago when Mike Tyson retired from the sport he was shot, completely finished," the Matchroom boss told BBC Sport. "It was actually sad to watch then, 20 years ago."
Brooklyn-born Tyson became the youngest world heavyweight champion when he beat Trevor Berbick aged 20 in 1986, and was the first to simultaneously hold the WBA, WBC and IBF titles a year later.
Though Tyson fought in an exhibition against fellow veteran Roy Jones Jr in 2020, Hearn - who was sat next to 'Iron Mike' at an event in Los Angeles in August – predicts the comeback will "only end in tears".
"I'm in awe of him - he's one of my favourite ever fighters, one of the greatest of all time - but he's a 58-year-old man," Hearn added.
"You only need to speak to him and look at him to know this guy should not be in a ring again."
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The fight, which will be held at the 80,000-capacity home of NFL team the Dallas Cowboys, is a professional contest with a string of conditions.
Paul, 31 years younger than Tyson at age 27, has mostly met ex-UFC fighters, with his solitary defeat coming against British boxer Tommy Fury in February 2023.
He has defended the decision to fight Tyson despite the age difference, saying the hall-of-famer's experience levels the playing field.
But Hearn – who initiated a defamation case against Paul after the American accused him of bribing boxing judges in October 2022, with a court date reportedly set for this month – disagrees.
"If I was Jake Paul I'd just feel a little bit embarrassed to be honest with you. It's a liberty," Hearn said.
"This is dangerous, irresponsible and, in my opinion, disrespectful to the sport of boxing."
The pair were due to fight on 20 July but Tyson had an ulcer flare-up that forced the match with the YouTuber to be rescheduled.
"That was the moment they should have realised that this was actually a bad idea," Hearn added.
"Everybody loves a dollar bill, including me, but sometimes the green-eyed monster can make you some bad decisions - and I think this is one of them."
Hearn to watch Taylor v Serrano then leave
Hearn acknowledges the commercial value and mass appeal of Tyson v Paul, which will be broadcast live on streaming platform Netflix.
Paul has a huge presence on social media, with 26.8m followers on Instagram and 20.8m subscribers on YouTube.
His transition to boxing has helped Serrano's career skyrocket - she is signed to his promotions company and features on the cards for his fights, while Paul was key in making the historic first Taylor bout happen at Madison Square Garden in 2022.
Despite his criticism of the main event, Hearn defends Matchroom fighter Taylor's involvement in the card.
Ireland's undisputed light-welterweight champion Taylor will face Puerto Rican Serrano in arguably the biggest fight in women's boxing.
Taylor, 38, defeated Serrano, 35, via split decision in an all-time lightweight classic.
"We received a massive offer for Katie. I'm not going to tell her she's not allowed to fight on that card," Hearn said. "Financially it's the biggest purse of her career.
"I won't be watching the main event. We'll be there defending the belts, and then I'll be off."
