The upcoming women’s junior lightweight title unification bout between Mikaela Mayer and Alycia Baumgardner may come down to pure grit, according to Claressa Shields.

Shields, the three division titlist and Michigan native, was recently asked who she thinks will win the contest between the heated American rivals, and while she did not answer the question head-on, she did indicate whom she believes has proven herself more in situations of extreme duress.

That would be IBF, WBO champion Mayer.

Shields noted that she was impressed with how the Southern California native had to dig deep in her competitive fight with Maiva Hamadouche last November, which Mayer won by unanimous decision to unify titles. Shields, however, is not sure if Baumgardner has a similar fight on her résumé that compelled her to fight, as she put it, in the trenches.  

“I think I’ve seen Mikaela go through the trenches,” Shields said of Mayer in an interview with The DAZN Boxing Show. “Not just in the [Olympic] trials, but in sparring, and [in] world championships, she’s always been at the highest level, always medaling. The only place she didn’t medal was in the Olympics, but she got very, very close. She’s improved and she’s calling out all the girls to be undisputed.

“I think Alycia is the 'bomb'. She’s classy, she’s sassy. She’s got the muscles, she’s got the looks. She can box, but I’m just wondering, can she switch up the game plan? Because if you got out there and ‘oh it’s gonna be a boxing match’, either girl can win. But if Mikaela goes out there and applies the pressure and makes it like she did against Hamadouche, Alycia not gonna be able to look back and look all cute and stuff.”

Baumgardner was virtually unknown in the boxing world until she knocked out titlist Terri Harper with one punch last year. Since then, the Michigan native has been on the rise.

The Mayer-Baumgardner bout will act as the chief supporting bout to the undisputed middleweight bout between Shields and Savannah Marshall October 15 at the O2 Arena in London.

“She gon’ have to put it on the line and I’ve never seen Alycia have to see where her gas tank is, but we’ve seen Mayer go 10 rounds straight, just go, just go,” Shields continued. “And I think that’s something that’s gonna play a part in the fight. I think both girls are very, very durable, and I can’t wait to see this great addition to the undercard.”