Anthony Crolla and Ricky Burns are to fight at lightweight on October 7 at the Manchester Arena as they attempt to rebuild their careers following defeat.
Scotland's Burns, 34, lost his WBA light-welterweight title to the classy Julius Indongo in April and returns to the division in which he secured his finest wins.
Similarly, the 30-year-old Crolla lost his WBA lightweight title to Jorge Linares last September and then their rematch in March.
A further defeat for either fighter would likely take a return to world level beyond them, and at a time when there is optimism fellow British lightweight Luke Campbell can win the WBA title against Linares next month.
"A win puts us back in the mix for titles," Manchester's Crolla said. "I'm not going to say the loser has nowhere to go, but it's going to be a tough road back.
"We're both coming off losing our world titles and the incentive is to win the fight and get back in the frame.
"I could have a tune up fight on the undercard of somewhere and an easier opponent to get me back into things and then a big fight after but I'm not interested in that.
"(A fight between us has) nearly happened before a good few times, a few years ago at super-featherweight and again at lightweight.
"It's been talked about for years now. It looked like it wasn't going to happen but it's good now we're finally going to meet."
Burns also had the option of fighting promising compatriot Josh Taylor at 10st, but he said: "I've been making 140lbs too easily and I've had enough notice for this fight.
"Although those last pounds will always be tricky I'm happy to be back down at 135lbs.
"I'm always saying to Tony (Sims, his trainer) I've got two or three more years left. At this stage of my career I don't see the point in getting an easy win. I'd rather go in with a big name.
"If I win, I'm going to progress and hopefully get another title shot."