Tyson Fury and Deontay Wilder's final news conference descended into chaos as they clashed on stage three days before their heavyweight bout in Los Angeles.
A packed room watched the verbal jousting and, after Fury's words saw Wilder grow visibly more irate, the pair began pushing during a face off.
Their teams got involved, prompting 60 seconds of mayhem.
Fury removed his shirt as security intervened, before the duo and their entourages were cleared from the stage.
What had started with both men hyping the Staples Center bout developed into an exchange of insults, with both men promising a knockout.
Speaking while barechested to BBC Sport's Mike Costello, Fury added: "I took my shirt off to get involved and frightened them all away.
"Everyone thinks the rivalry is fake but they can guess again as it nearly went off again.
"Wilder thought he needed to spit in my face or whatever he was doing, shouting. He feels pressured, you can see the pressure he is under out there."
What prompted the chaos?
After both men left the stage, one journalist could be heard describing the scenes as "crazy".
After opening speeches by each fighter, Fury seemed to grow into proceedings and elected to stand to answer questions, during which he questioned why American Wilder's profile was small in his homeland despite his status as WBC world heavyweight champion.
"On Saturday night the whole world will know him as the person who Fury knocked out," said the Briton, 30.
"Up until he had 30 fights he was reserved. This swagger is not genuine, it's fake - a snide and a fraud. I look at him and don't see a bad man, I see a pretender."
Wilder - who had earlier said Fury had made his name in a "small country" - grew louder but remained seated.
But when the pair posed for head to heads, 33-year-old Wilder was shouting in his opponent's face, before a melee engulfed the stage.
Have your say
More Sports Headlines
- Mali secure first U-20 AFCON title on penalties
- Jeffrey Schlupp scores as Palace march on in FA Cup
- Basketball Africa League: Professional competition to launch in 2020
- Afriyie Acquah scores as Empoli beat Sassuolo in Serie A
- Mission International School, Happy Days Academy dominate Joy Kids Olympics second leg
- Kevin-Prince Boateng: Barca striker burgled during La Liga debut vs Valladolid
- Sergio Ramos and his 25 Real Madrid red cards: a retrospective
- Ramos sent off as Real Madrid suffer shock home loss to Girona
- I was destined to be world champion - Commey
- SCOREBOARD: Results from top European leagues
- Messi scores one penalty but misses another in Barca win
- Morocco to bring in VAR technology for all top-flight league games
- CAF CC: Ex-Kotoko star Yusif Chibsah thinks key to qualifying is winning away matches
- Tanko hints at call-ups for Kotoko players for Kenya Clash
- I’m not scared of Tagoe - Richard Commey