Claressa Shields scoffed at Savannah Marshall’s claim Tuesday that she has more heart than the self-proclaimed “GWOAT.”

Shields dismissed Marshall during a conference call as a weight bully built up by beating smaller opponents who’ve taken fights against her on short notice. Marshall, the only boxer who has defeated Shields as an amateur or pro, has knocked out 83 percent of her professional opponents (12-0, 10 KOs), yet she will take a steep step up in class when she faces Shields in a middleweight title unification fight September 10 at O2 Arena in London.

“I can’t believe she said that she got heart,” Shields said. “That was just insane right there. No, she don’t have no heart. She won’t fight against no girl unless it’s a week notice, three weeks’ notice, I mean three days’ notice, or it’s a girl fighting at 147 coming up to 160. She hasn’t fought against a true 160-pounder or a girl who’s near her size. So, her talking about she got heart, that’s a myth.”

Shields (12-0, 2 KOs) also questioned Marshall’s assertion that she has more intelligence in the ring than an elite-level boxer who has barely lost any rounds on her way to winning world titles in three weight classes.

“As far as her [having] a better IQ than me, all the girls that beat her in the amateurs, I beat them the next day,” Shields said. “So no, she don’t have a better IQ than me. She got lucky the night that we [fought], that she won the world championship. But, you know, that’s just luck. But you can’t say she better than me. We fought in four different tournaments together, we been pro at the same time. You were signed to Mayweather Promotions and you still didn’t accomplish nothing.

“But I’m a 12-time world champ, and you’re a one-time world champ. But you say that, you know, you’re a better fighter than me. That’s just inaccurate. No, she’s not. She can’t box better than me, not a better IQ. You’re already talking about retirement after the fight, so she’s already got that mindset. We all know what’s going on. Payday! Payday!”

That said, Shields wants nothing more than to avenge her 14-8 loss to Marshall at the AIBA Women’s World Boxing Championships in May 2012. That points defeat remains the 27-year-old Shields’ lone loss as an amateur or professional boxer.

The Flint, Michigan native went on to earn gold medals at the 2012 Summer Olympics in London and the 2016 Summer Olympics in Rio de Janeiro. She later won world titles at 168, 160 and 154 pounds as a pro, and became the undisputed champion in the middleweight and junior middleweight divisions.

England’s Marshall, 31, won the then-vacant WBO middleweight title in October 2020, after Shields dropped down to the 154-pound division.

The Shields-Marshall grudge match will be the main event of a Sky Sports broadcast in the United Kingdom and Ireland. It’ll also headline an event ESPN+ will stream in the United States.

Mikaela Mayer (17-0, 5 KOs), Shields’ former Olympic teammate, will square off against rival Alycia Baumgardner (12-1, 7 KOs) in the co-feature that’ll immediately precede Shields-Marshall. Mayer, of Colorado Springs, Colorado, and Baumgardner, of Bingham Farms, Michigan, will fight for Mayer’s IBF and WBO belts and Baumgardner’s IBO and WBC crowns in their 10-round, 130-pound title unification fight.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.