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Oleksandr Usyk is a professional Ukrainian boxer who has held multiple world heavyweight titles. By 2019, Usyk had defeated five current or former world champions. These boxers include Murat Gassiev, Tony Bellew, Dereck Chisora, and David Haye. Usyk's victories over Gassiev and Bellew earned him the WBA (Super), IBF, WBO, and The Ring heavyweight titles. He defeated Chisora and Haye in 2020 to retain his titles.