Claressa Shields has branded Savannah Marshall a “liar” and promised to avenge her loss to the British fighter.

Shields holds all the other belts in the division and says Marshall is only a world champion thanks to her.

“Savannah Marshall is a liar,” she told BBC Sport.

Shields reserves particular anger for how she believes her switch into mixed martial arts was portrayed by Marshall.

“When I first signed the contract to fight for the PFL [in mixed martial arts] she made it all about her,” Shields said.

“[She was saying] ‘she’s running from me, she’s scared of me’ but I never retired from boxing. I’m still the owner of three belts.

“The only reason she is WBO champion is because I had to vacate that belt to fight for undisputed championship at 154lbs. Other than that I would still be undisputed at 160lbs.”

Shields continued: “She didn’t fight the champion to get the belt. Her and [promoter] Eddie Hearn whined and cried about it.

“They made tears about it and the WBO said I had to vacate.”

Super-fight nine years in the making

Marshall, 30, who successfully defended her title with a quick knockout of Lolita Muzeya, has repeatedly goaded Shields from afar over their amateur days.

The Hartlepool fighter remains the only blemish on her rival’s fighting record, beating a 17-year-old Shields at the World Amateur Boxing Championships in 2012.

Shields, still only 26, is the only boxer – male of female – in the sport’s history to hold undisputed championships in two different weight classes concurrently and believes her achievements are being used by Marshall to bolster her own standing.

“She just makes everything about her and it’s not. Her whole career is based off of me,” Shields said.

“I’m 26 now, what have you [Marshall] done in that time span? You were signed to Floyd Mayweather, did you make a name for yourself in the US? No.”

She added: “The only thing she can say is she beat Claressa Shields when she was 17. That’s it. Other than that, what else has she accomplished in her career?”

‘This is for my legacy’

The super-fight is expected to take place in the UK, with Marshall getting home advantage. Shields insists she has no issue travelling despite being the unified champion.

“Everybody needs a good dance partner. I’m happy she’s talking more because that’s needed in boxing, in women’s boxing,” she said.

“I’m going to right it – not because she talks so much but just for myself. I am going to fight her and beat her. It’s for my legacy.

“[It’s not that] she’s an outstanding fighter, more like since the blemish is there from the amateurs I want to fight her just to cement myself more as the GOAT.”

‘She’ll see what real power is’

Marshall has nine knockouts in 11 fights and is undefeated, like Shields, who has two knockouts in her 11 bouts.

However, Shields has already been a world champion at light middleweight, middleweight and super middleweight in her pro career and revealed she was unimpressed by her rival’s latest performance despite the quick nature of the victory.

“When we fight, then they’ll see what real power is,” she predicted.

“In her last fight, she lost the first round. Let’s just be clear, she lost the first round. She didn’t know what to do when that girl was on her like white on rice.

“That’s going to be me times a hundred and I don’t gas out. We all know that. I don’t gas out. I’ve got the skills. I’ve got the stamina. I’ve got the speed.”