Derek BrunsonAn injury to Karlos Vemola has forced a shift on the UFC’s yearend card. Strikeforce veteran Derek Brunson will fill in for the Czech fighter against the heavy-hitting Chris Leben. USA TODAY Sports first reported the news Tuesday.

Brunson was originally slated to appear on the upcoming season of The Ultimate Fighter before Showtime refused to release him from his contract, despite the fact he had already made weight and traveled to the show. Brunson is coming off the first two losses of his career as he heads to the Octagon, dropping a close split decision to Kendall Grove on a week’s notice and suffering a knockout loss to Ronaldo “Jacare” Souza in August.

The UNCP product will face off with the hard-hitting Chris Leben in his UFC debut. Leben will be returning to the cage after a yearlong suspension for painkillers, the second career suspension for the longtime UFC veteran.

The UFC’s yearend fight card will take place December 29 at the MGM Grand Garden Arena in Las Vegas, Nevada. The UFC 155 bill will be headlined by a heavyweight title rematch between UFC heavyweight champion Junior dos Santos and former champion Cain Velasquez.