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A big night for women's boxing is set to go down on Sept. 10 at the O2 Arena in London. The card will feature two big championship fights including a main event for the undisputed middleweight championship between WBA, WBC and IBF champion Claressa Shields and WBO titleholder Savannah Marshall.

In just 12 fights, Shields has already proven herself to be arguably the greatest female boxer in history, winning titles at junior middleweight, middleweight and super middleweight, including becoming undisputed at junior middleweight. After beating Marie-Eve Dicaire in March 2021, Shields took a brief break from boxing to pursue a mixed martial arts career in the PFL, losing her second bout. She then returned to boxing this past February to defeat Ema Kozin to retain her middleweight titles.

Marshall is the only boxer to have ever defeated Shields in boxing, scoring an amateur win in 2012. That win has led to a long history of talks around a potential pro showdown. Marshall is also 12-0 as a professional and won the WBO middleweight title in October 2020, successfully defending the belt three times so far and setting up the undisputed showdown with Shields.

In the other featured bout of the card, WBO and IBF super featherweight champ Mikaela Mayer will battle WBC champ Alycia Baumgardner in a unification showdown.

Mayer is 17-0 and won the WBO title in October 2020 with a win over Ewa Brodnicka. She added the IBF title in November 2021, beating Maiva Hamadouche in one of the best fights of the year.

Baumgardner has only suffered one defeat in her career but has since won six straight fights, including knocking out Terri Harper in November 2021 to win the WBC title. She defended her belt in April with a win over Edith Soledad Matthysse.