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Amanda Nunes has been forced out of her planned women's featherweight title defense against Megan Anderson at UFC 256. The fight, which was set to headline the Dec. 12 pay-per-view, was expected to be Nunes' second defense of the 145-pound championship.

The news was first reported by ESPN's Brett Okamoto before being confirmed by Anderson, who tweeted, "Wishing Amanda a speedy recovery, UFC are rescheduling the bout for a date early next year. The goal remains the same We'll be ready."

Nunes, who also holds the women's bantamweight championship, last fought in June when she easily defeated Felicia Spencer. That victory ran her current winning streak to 11. With Nunes having an iron grip on the division, fresh challengers were needed, and Anderson's knockout win this past February to run her winning streak to two was enough to punch her ticket to a title shot.

The reason for Nunes' withdrawal has not been confirmed, though Anderson gave a statement to ESPN saying there was a "serious medical issue" that has forced the UFC to postpone the bout to 2021.

Petr Yan's bantamweight title defense against Aljamain Sterling will likely serve as the event's headliner. The fight marks Yan's first defense of the title he won by defeating Jose Aldo in July.

The location of UFC 256 has not yet been confirmed by the promotion, though it seems likely the event will be held at Las Vegas' UFC Apex facility.