MyMMANews first reported Avila’s withdrawal from the Dec. 18 card. It is currently unclear if Pennington will receive a replacement opponent. UFC Fight Night 199 takes place at the UFC Apex in Las Vegas and is headlined by a heavyweight showdown between Derrick Lewis and Chris Daukaus.
The 33-year-old Avila has been victorious in three of her first four promotional appearances — including a third-round submission of Julia Stoliarenko in her last outing at UFC Fight Night 190 on June 26.
A former bantamweight title challenger, Pennington is coming off back-to-back decison wins over Marion Reneau and Pannie Kianzad.