LONDON (AP)Claressa Shields avenged her only career defeat when she beat Savannah Marshall by unanimous decision and became the undisputed women’s world middleweight champion on Saturday.

Shields lost to Marshall in their amateur days in 2012 but, in a stunning bout at a sold-out 02 Arena, Shields relieved Marshall of her WBO belt to add it to her WBC, WBA and IBF crowns.

The fight topped Britain’s first all-female card, and was supposed to take place five weeks ago but was postponed following the death of Queen Elizabeth II.

Marshall, of Britain, withstood a flurry of early blows before pinning Shields to the ropes in an explosive first round.

Marshall caught Shields early in the second, briefly putting the American back on her heels.

Shields possessed the speed but Marshall had the power, and the pace continued through to a brutal fifth round with both women landing hefty hooks.

The busier Shields was undoubtedly ahead on the cards by the eighth but a cut appeared on her forehead as Marshall found a way through her defense.

Marshall (12-1) knew she needed a knockout and threw everything at Shields (13-0) in another gripping final round, but the American landed the cleaner shots.

The judges scored it 96-94, 97-93 and 97-93.

Also, Alycia Baumgardner beat fellow American Mikaela Mayer in the narrowest of split decisions to become the unified world super-featherweight champion.

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