The planned UFC 256 headliner between dual-division champion Amanda Nunes and featherweight challenger Megan Anderson has been scrapped from the Dec. 12 fight card in Las Vegas.

Sources confirmed that Nunes was forced out of the bout with an undisclosed injury, following an initial report by ESPN’s Brett Okamoto.

The injury is apparently one that Nunes is expected to recover from fairly quickly, as Anderson tweeted that the UFC is rescheduling the bout for early 2021.

Nunes vs. Anderson was expected to headline the UFC 256 fight card with a co-main event featuring bantamweight titleholder Petr Yan making the first defense of his belt against Aljamain Sterling.

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UFC 256 main event’s revolving door

UFC 256 was originally slated to feature a welterweight championship fight between champion Kamaru Usman and challenger Gilbert Burns. Nunes vs. Anderson was to serve as the co-main event. Then the UFC hoped to ink Yan vs. Sterling to make its final 2020 pay-per-view a championship tripleheader.

Those plans went awry when Usman indicated that he would not be ready to fight on Dec. 12, citing the need for more time to heal from unspecified injuries.

Nunes vs. Anderson was then moved to main event status and Yan vs. Sterling signed to take the co-main event slot.

Now, with Nunes vs. Anderson at least delayed until 2021, the promotion is left to determine whether it will move Yan vs. Sterling into the headlining slot and/or try to ink another championship bout. But there are few, if any, championship options left as the year winds down.

UFC 255 is already slated to be a championship doubleheader with Deiveson Figueiredo defending the men’s flyweight title opposite Alex Perez in the headliner, and women’s flyweight champion Valentina Shevchenko expected to face Jennifer Maia in the UFC 255 co-main event.

Heavyweight champion Stipe Miocic, newly minted light heavyweight champ Jan Blachowicz, featherweight titleholder Alexander Volkanovski, and strawweight champion Zhang Weili are the only champions without fights booked.

Miocic isn’t expected to fight again until 2021, likely defending against Francis Ngannou. Zhang was also not anticipating a bout until 2021 with the UFC working to match her with Rose Namajunas.

Volkanovski is likely to defend against Brian Ortega next, which might be a possibility for 2020, though it has been most recently targeted for February of 2021.

UFC president Dana White initially had planned for middleweight champion to move up and challenge Blachowicz for the new titleholder’s first defense. With Nunes now out and Glover Teixeira’s performance over the weekend and his current winning streak, perhaps Teixeira could make a quick return to challenge Blachowicz in December.

For now, however, the UFC has not commented on Nunes’s withdrawal or plans for a possible replacement bout.