The 27-year-old won via unanimous decision after a stunning bout to add Marshall's WBO middleweight belt to her WBC, WBA and IBF crowns.
She said: "Claressa is a brilliant fighter - not as fast as I thought! Ahead of everyone else by a country mile." She would do horrendous things to Katie Taylor. One wrote: "Claressa Shields is right up their with one of the best women to ever lace up a pair of boxing gloves, but the GWOAT is and always will be Katie Taylor." One said: "Itโs time to admit that Claressa Shields is the number 1 p4p female fighter in the world. 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 defence.