Tony Bellew takes on undisputed cruiserweight world champion Oleksandr Usyk at Manchester Arena on Saturday night.
It is the first ever undisputed world title fight to be held in the UK.
Bellew heads into the fight as a big underdog given the pugilistic mystique of Usyk, which was shown in July when he claimed his straps against Murat Gassiev.
Bellew is coming off the back of two grudge match knockout wins over David Haye at heavyweight, returning to his preferred weight division.
Eddie Hearn promotes the Liverpudlian and has built a good friendship with the 35-year-old since signing him to Matchroom Sport.
Ahead of Saturday’s momentous bout, Hearn told iFL TV: “This is the best and biggest fight I’ve ever promoted. I was thinking that the other day.
“It don’t get any bigger than this for me, and that includes being bigger than Joshua-Klitschko, honestly.”
Anthony Joshua’s incredible 11-round barnstormer against Wladimir Klitschko in April 2017 is widely considered as one of the greatest boxing matches of all time.
Roughly 80,000 packed into Wembley to witness AJ conquer in the legacy fight, but Hearn insists the 20,000 people in Manchester Arena on Saturday night will be witnessing an even bigger occasion.
“In terms of what’s on the line, in terms of how everything’s happened, in terms of the Tony Bellew story, in terms of Usyk being in his absolute prime; this is the biggest fight I’ve ever promoted,” Hearn continued.
“I just can’t believe it’s actually happening.
“This is not about money, trust me when I say that. This is about legacy, this is about a defining moment. This is about wanting to know how good you are. And that’s great sport.”
Hearn went on to praise Bellew’s motives regarding Saturday, saying: “He won’t ask me how much money he’s making.
“He won’t ask me about the pay-per-view buys. He just says: ’Those belts are coming home with me.’
“Tony is a student of the sport – he knows what he’s got to do.
“This is a fight between such an elite fighter, such a genius in Oleksandr Usyk, against this geezer who has just got the will to win, the knack to win.
“This is the best fight I’ve ever promoted – this is everything, the undisputed cruiserweight world championship.
“These are the fight that you look at when you look back through history. This is up there.”