Stevie Ray and Brendan Loughnane will both compete in $1m (£840,000) winner-takes-all title fights at the 2022 Professional Fighters League (PFL) World Championship on Friday.
Scotland's Ray, 32, fights first against Olivier Aubin-Mercier in the lightweight final in New York.
Manchester's Loughnane, 32, follows against Bubba Jenkins in the featherweight showpiece.
The $1m prize would be a record amount won by a Briton from a single MMA bout.
Former UFC middleweight champion Michael Bisping's reported $540,000 (£452,000) earned against Georges St Pierre in 2017 is the current highest.
The event at the Hulu Theatre at Madison Square Garden is described as the "richest night in MMA" by the PFL and could cap a successful year for British mixed martial arts, just three months on from Leon Edwards' UFC welterweight title win.
Edwards became only the third British MMA champion from a major promotion with his win over Kamaru Usman, following Bisping in 2016 and former Bellator light-heavyweight title holder Liam McGeary, in 2015.
Ray, who was born and lives in Fife, also has the chance to become the first champion in a major MMA promotion from Scotland.
'Regardless of what happens, I'm proud'
Ray, who has won 25 of his 35 professional fights, retired in 2020 after parting ways with the UFC.
As a free agent, Ray was struggling with knee injuries and with a lack of fight opportunities coinciding with the coronavirus pandemic, made the impulsive decision to end his career.
"I was a little bit emotional with the whole departure and then the fact I was injured, I ended up retired. It was an emotional decision, I was never ever done," Ray told BBC Sport.
Around two years went by with Ray in limbo, wondering whether he would ever compete again and considering a career as an MMA coach, manager or personal trainer.
It was then that Ray was approached by the PFL, who offered him the opportunity to compete in their annual lightweight tournament.
He accepted and has not looked back, winning two of his three fights this year to reach the final.
"From where I came from, being brought up with not much money in a council estate, regardless of what happens in the next fight, even if I lose I'm very proud of what I've done," said Ray.
"I've been able to change my life and my family's life."
He continued: "Obviously I'm training my butt off to go and try and win and it would be the cherry on the cake, but like I said, worst case scenario, even if I lose, I've still made a lot of money this year.
"Looking back two and a half years ago when I was done, I'm in a much better position now."
In 33-year-old Canadian Aubin-Mercier, Ray faces an opponent who is unbeaten in the PFL, winning all five of his fights.
Ray is the underdog with bookmakers but says he has "left no stone unturned" in his training, to give himself the best possible chance of winning.
Should Ray win the title and the prize money, he's already decided the first thing he's going to buy.
"A pizza. But the first kind of thing that costs a bit of money would be a holiday," said Ray.
"Then just a good Christmas, and I've got some plans to help my mum buy a house and stuff like that too."
'I want to be up there with Fury, Rashford and Hatton'
Loughnane has won all three fights in the PFL this season, extending his professional record to 25 wins and four defeats, and has bettered last season's result where he lost in the semi-finals.
His first amateur fight was in 2008 which he earned £150 for, and says it has been a "wild journey" to becoming a world title challenger.
In 2019, Loughnane missed out on a UFC contract, but regrouped to sign with PFL, becoming the most successful British fighter in the promotion since it was founded in 2017.
Despite the stakes, Loughnane is more passionate about the prospect of writing himself into Manchester sporting folklore.
"Winning the title will cement my legacy in Manchester, it would mean everything to me, I'm a proud Mancunian," said Loughnane.
"I want to put myself alongside the [Marcus] Rashfords, the [Tyson] Furys, the Ricky Hattons.
"We're flying and I think me winning this belt now is really going to put the icing on the cake for British MMA."
Like Loughnane, 34-year-old opponent Jenkins has won all three fights in the PFL this season.
The American has relied heavily on his wrestling background in the past, but Loughnane, who prefers the stand-up, is confident of finding a route to victory.
"This fight means everything. Twelve years I've been doing this and I want that gold, that title," he said.
"He's going to have to kill me in there - it's get rich or die trying."
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