Savannah Marshall "won't back down" from Claressa Shields' "confrontational" personality when they cross paths, says BOXXER promoter Ben Shalom.
Shields makes her UK debut on the same bill as Marshall on December 11, setting up an undisputed middleweight championship fight next year, in what would be the biggest women's bout ever.
The rival champions have both signed with BOXXER, putting them on a collision course, and Marshall recently enhanced her reputation by winning an exciting shoot-out with Lolita Muzeya by knockout.
Shalom told Sky Sports about the Shields-Marshall rivalry: "People don't realise how headstrong Savannah is. She won't take any rubbish.
"She's sick of Claressa.
"Claressa is one of the best-known fighters in the sport but Savannah is convinced that she's better than her.
"Claressa is very antagonistic in person - that's her nature. She is very confrontational.
"We know they don't like each other.
"But they are also both elite athletes who want to prove who's the best in the sport.
"Claressa has struggled to find opponents worthy of fighting her, which led her to MMA. Now this is an extraordinary opportunity for her because, in Savannah, she might have met her match.
"They know each other from the amateurs.
"It was a very easy fight to make because they both want it. They both know it's a legacy fight, the best fight out there."
Their feud stems from when Marshall beat Shields in an amateur fight in 2012 - it is the only time that the feted American has been beaten, amateur or pro, in her career.
Shields has won gold medals at consecutive Olympics, world titles in three divisions and become undisputed in two.
Unbeaten Marshall is the WBO middleweight champion - Shields owns the IBF, WBA and WBC belts in the same division.
Shields is competing in her second MMA fight on October 27, then defends her world titles against mandatory challenger Ema Kozin on December 11 on her UK debut.
"We did a deal with Salita Promotions for a two-fight deal with Claressa," Shalom said. "She has a mandatory that she has to take care of.
"We are looking for an extremely tough fight for Savannah too.
"We want all the belts on the line."
Sky Sports Boxing schedule
October 31 - Top Rank in New York
Jose Zepeda vs Josue Vargas
November 6 - Top Rank in Las Vegas
Mikaela Mayer vs Maiva Hamadouche - IBF and WBO super-featherweight titles
November 6 - BOXXER in Liverpool
November 20 - BOXXER in London
Richard Riakporhe vs Olanrewaju Durodola
Caroline Dubois professional debut
November 20 - Top Rank in Las Vegas
Terence Crawford vs Shawn Porter - WBO welterweight title
December 11 - BOXXER
Claressa Shields vs Ema Kozin
December 11 - Top Rank in Las Vegas
Vasiliy Lomachenko vs Richard Commey
December 17 - Top Rank in Montreal
Artur Beterbiev vs Marcus Browne - IBF and WBC light-heavyweight titles
February 26 - Top Rank in Glasgow
Josh Taylor vs Jack Catterall - undisputed super-lightweight title