James DeGale (right) defeated France's Alpay Kobal in March
James DeGale will defend his British super-middleweight title against George Groves at The O2 on 21 May, promoter Frank Warren has announced.
Unbeaten Commonwealth champion Groves used to box at the same gym as DeGale and defeated the Olympic champion in their only meeting as amateurs.
The 22-year-old edged a majority decision on the way to winning the first of two successive ABA titles.
The relationship between the pair has since turned sour.
And the London duo have not spoken since Groves' victory over 25-year-old DeGale.
"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."
Since turning professional after the Beijing Olympics where he won the middleweight title, DeGale has put together 10 successive victories securing the British title in his ninth bout.
His last fight was against veteran Frenchman Alpay Kobal on 12 March, who he stopped in the fifth round.
Groves, meanwhile, has won all 12 of his fights and picked up the Commonwealth belt in his ninth outing.
In his last contest on 5 March he recorded a fourth-round win against Ghanaian Daniel Allotey.
Groves responded to DeGale's comments by saying: "Everyone wants to smash DeGale's face in. He's the most arrogant, egotistical fighter out there.
"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," he added.
Top of the card at The O2 will be Nathan Cleverly's WBO light-heavyweight title challenge against Germany's Juergen Braehmer.