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.