James DeGale today opened hostilities for his grudge match against George Groves with a brutal verbal assault on his bitter rival.
One of the most eagerly awaited domestic showdowns of recent times, to be staged at the O2 on May 21, was announced at a lively press conference in London.
The source of the enmity dates back to 2006 when Groves defeated his Dale Youth ABC stablemate in their only meeting as amateurs.
DeGale, the current British super-middleweight champion, was edged on a majority decision that he disputes to this day and their relationship has since deteriorated.
The disappointment was later eased by his qualification for the 2008 Olympics and subsequent gold medal triumph, but the animosity between the pair persists.
"This is personal. If I'm brutally honest, George and me do not like each other," said DeGale.
"He's lived in my shadow for half his life. He's always been the ugly kid behind James DeGale.
"He's going to be bitter and jealous and we have to sort it out in the ring.
"Ask any of the coaches in the gym, I used to play with George in sparring.
"When I was in the amateur gym I used to move around the ring and pick his head off."
A fiery exchange saw Groves, the Commonwealth champion who trains alongside David Haye under the guidance of Adam Booth, heavily provoked by a boisterous DeGale.
"Ugly kid, you're getting it! You're getting it, moron! In real life you're worse - look at you, ugly boy. Moron," he said.
"You think you're David Haye, the way you speak the way you fight! A mini David Haye.
"You've got worse, ugly kid. You silly, ugly boy, you're deluded."
Since overcoming an uncertain start to life as a professional, when many questioned his ability to make the transition from the amateur ranks, DeGale has established himself as a superb prospect.
The 25-year-old has reeled off 10 victories, topped by a highly-impressive ninth-round stoppage of the vastly more experienced Paul Smith to seize the British title in December.
Groves has won all 12 of his fights and claimed the Commonwealth belt in only his ninth outing, but his progress has slowed.
Having been widely tipped to prove more suitable to professional boxing than DeGale, he has since been overtaken by his rival.
However, the 22-year-old is confident he still has the measure of DeGale.
"Everyone wants to smash DeGale's face in. He's the most arrogant, egotistical fighter out there," said Groves.
"Our rivalry comes from the fact James DeGale was Olympic champion but number two in his own gym.
"When we fought there was a lot of hype about him, but look on YouTube, I beat him. It's there for everyone to see."
DeGale stated that Groves had been knocked out in sparring by Carl Froch, a claim that was denied with the younger fighter who insisted he was only knocked down.
Either way there is little shame in a novice being floored by Britain's WBC super-middleweight champion, though DeGale's trainer Jim McDonnell fears the fight has come too soon for Groves.
"George needs to improve a lot, his defence is terrible, it's wide open," said McDonnell.
"It's too early for George and he knows it. George, get your career back on track, learn your trade.
"A year ago this fight was a real 'who's going to win?'. But now everyone knows James will win the fight.
"Taking the fight now is about ego and it's madness. They're mad. He's trying to be David Haye, but he isn't David Haye."
Topping the card at the O2 will be Nathan Cleverly's WBO light-heavyweight title challenge against Jurgen Brahmer of Germany.
"Brahmer's a strong fighter with a great record and a great pedigree," said Welshman Cleverly, who may spar with DeGale in preparation for the fight.
"He was world amateur champion so obviously has a bit of class about him."