Carl Froch shoved George Groves in the face during a media appearance at Wembley as the tension mounts ahead of their 31 May rematch.
Tickets for the fight sold out in 75 minutes on Monday and already things are hotting up again between the duo.
Groves also confronted Froch's brother, Lee, after an indoor photoshoot, as both corners continue to fan the flames following their controversial November fight.
Groves says he will refuse to fight Froch unless the British Boxing Board of Control sanction neutral officials for their super-middleweight world title rematch at Wembley Stadium.
The 25-year-old Londoner has claimed the rematch, mandated by the IBF, will not go ahead unless the BBBofC allow a non-British crew of match officials.
Groves labelled the ninth-round stoppage by referee Howard Foster that handed Froch a controversial victory in November a "stonewall" robbery.
Promoter Eddie Hearn backed Groves' call for neutral officials, claiming the keenly-anticipated rematch will be the "biggest fight in British boxing history".
"It was a stonewall robbery first time, everyone knows it, and that's why I've requested neutral officials," said Groves.
"It's conditional on the fight going ahead.
"I don't believe in fate, but I do believe in everything happening for a reason.
"Maybe I had to go through that decision, that first fight, to get to the point where I can fight at Wembley, in my home city, in front of my home fans.
"I couldn't be more excited about this fight now.
"The first fight we went in believing: now we go in knowing.
"More importantly Froch knows. Apart from the gift in the ninth round last time out, he's got nothing. He's absolutely spent."
Groves nonchalantly completed a Rubic's Cube puzzle while Froch responded to his claims at Monday's press conference at Wembley Stadium to launch ticket sales.
Promoter Hearn backed Groves' call for neutral referees, but refused to apportion any blame to Foster for Froch's November victory.Suggest a correction