Wikipedia - Christina Hammer
Christina Hammer (born 16 August 1990) is a German boxer. As a professional, she has held multiple world championships in two weight classes, including the WBO female middleweight title from 2010 to 2019, becoming the youngest boxer to win a WBO world title; the WBC female middleweight title between 2016 and 2018; and the WBO female super-middleweight title in 2013. She also challenged once for the WBO female light-middleweight title in 2014 and once for the undisputed female middleweight championship against Claressa Shields in 2019.
Since Hammer's victory against Zita Zatyko, she has earned Fighter of the Year by the WBF and WBO; she was awarded BDB's Female Boxer of the Year; and the WBO awarded her with the WBO Diamond Ring for exceptional performance. As of February 2019, Hammer is ranked as the world's second best active female middleweight by The Ring and BoxRec, and the seventh best active female, pound-for-pound, by ESPN.
Hammer is known for her patient and methodical boxing style, wearing her opponents down with jabs and increasingly aggressive follow-up rights. Since November 2021 she is signed by Wasserman Boxing and managed by Daniel Todorovic of O1NE Sport GmbH.