Guillermo Rigondeaux back in to face John Riel Casimero: Will Nonito Donaire now rematch Naoya Inoue?

The original plan on Showtime was to have the 40-year-old Cuban face the Philippines' Casimero, 31, for the latter's WBO title. It was then decided to make the switch to an all-Filipino champion vs. champion bout, with Rigondeaux tentatively set to fight on the undercard against an undecided opponent.

Now that Donaire has withdrawn from the clash, it will indeed be Casimero vs. Rigondeaux in August.

Meanwhile, Donaire — who caught the eye winning another world title at the age of 38 in May by knocking out France's Nordine Oubaali in four — could very well move straight to the other big fight he craves, a rematch with WBA, IBF and The Ring titleholder Naoya Inoue.

Inoue vs. Donaire 1 was the final of the World Boxing Super Series bantamweight final on Nov. 7, 2019. The pound-for-pound ranked Japanese fighter won via unanimous decision to take home the Muhammad Ali Trophy, but Donaire remains insistent he can avenge the result if given another 12 rounds with 'The Monster'.