Carl Froch will defend his International Boxing Federation (IBF) and World Boxing Association (WBA) super-middleweight titles against George Groves later this year, it was announced Tuesday.
The all-British bout will take place either late in November or early December at a venue still to be announced.
Froch added the WBA belt to his IBF title when he beat Germany's Mikkel Kessler in a re-match at London's O2 Arena in May, with the unbeaten Groves winning the vacant WBA Inter-Continental title with a fifth round stoppage of Noe Gonzalez Alcoba on the same bill.
"I'm excited the first defence of both my belts is a big domestic clash," Froch told Sky Sports News.
"I am a proper fighter and a proper champion and I will always face my mandatory challenger rather than vacate the title.
"I've known George for a while, I've sparred with him and watched him grow and now he's my mandatory -- I will be pouring everything into my preparation for the fight and George will face the very best of me."
Meanwhile Groves said: "This is the biggest fight of my career and being a world champion is something that I dreamed of as a kid.
"I'm well ranked across all the governing bodies but fighting Carl is the one that I wanted the most."
Meanwhile Froch says he will not be guilty of over-confidence even though Groves has got a chance because higher-ranked fighters are unavailable.
"There won't be a danger of me underestimating George Groves, I don't underestimate anyone," he said. "I take every single fight very, very seriously. I prepare meticulously for every single fight.
"You hear people being dismissive on Twitter, but that's quite ignorant and I'm not going to go down that route."
Groves, unbeaten in 19 professional bouts, insisted suggestions his world title shot had come too soon were wide of the mark.
"The good world champions, they usually challenge for a world title around the 20-bout mark, around my age - 25 - and they usually have to take on older, more experience guys. They don't always come up short," Groves said.
"People are saying it's a step too far for me right now, but we know it's not. We know what we've got to do.
"I've been written off before and I've been the underdog before. I actually relish it."