Joshua, 32, immediately triggered his rematch clause, and then resisted an offer from Tyson Fury’s camp to step aside so that ‘The Gypsy King’ could have a world title unification bout with Usyk.
However, those plans have now been put on hold following Russia’s invasion of the Ukraine, which began on February 24.
Usyk, 35, was on a promotional tour in London when the conflict began, but promptly flew home before declaring he had taken arms in order to fight for his country.
In doing so, he joined boxing compatriots Wladimir and Vitali Klitschko, and Vasiliy Lomachenko, who have also joined the military as Russian attacks on the capital Kyiv, and surrounding areas, intensify.
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Hearn added that Joshua’s ‘top choice’ for his next fight would be Deontay Wilder, who is yet to return to the ring following his dramatic defeat to Fury in Last Vegas last October.
Wilder, 36, has said little about his future since the trilogy bout, other than to deny he is contemplating retirement and a fight with Joshua would represent a lucrative night for ‘The Bronze Bomber’ – whether it be in the UK or America.
Luis Ortiz, Otto Wallin and fellow British fighter Joe Joyce were also labelled targets as Joshua seeks a competitive bout.
Olympic silver medalist Joyce, 36, is unbeaten in all 13 of his professional fights, and the notion of an all-British clash would undoubtedly sell, although Wallin may be seen as a more obvious candidate.