CHICAGO, ILLINOIS - OCTOBER 12: Oleksandr Usyk of Ukraine walks to the ring before his Heavyweight bout against Chazz Witherspoon at Wintrust Arena on October 12, 2019 in Chicago, Illinois.
The Ukrainian, 34, has taken his rivalry with the British star to the next level ahead of their potential undisputed clash.
On Friday, Usyk posted a message on Instagram reading, "I decided to start preparing for a rematch with Anthony Joshua, a large number of my friends support me, all the rest of the good and peace, Thank God for everything.
Wladimir Klitschko, the 45-year-old who reigned atop the division from 2006 to 2015, had enlisted in the Ukrainian reserve military earlier in the month in advance of the invasion.
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