ALBUQUERQUE, N.M. >> The world’s former No. 1-rated female boxer has pulled out of her much-anticipated Ultimate Fighting Championship debut.

Promoter Lenny Fresquez told the Albuquerque Journal on Thursday that Holly Holm suffered a neck injury in training and had to withdraw from her scheduled fight with Colorado-native Raquel Pennington on Dec. 6 in Las Vegas, Nevada.

The 32-year-old Albuquerque boxer turned mixed martial arts fighter signed with the world’s largest mixed martial arts promotion in July after months of negotiations. Fans had hope Holm’s signing and her UFC debut would led to an eventual fight with UFC women’s bantamweight champion Ronda Rousey.

Last year, Holm announced her retirement from boxing to focus on an MMA career. She has a 33-2-3 record as a boxer and is 7-0 as an MMA fighter.