The preliminary portion of UFC 131 took a significant hit today, as it appears Ultimate Fighter Season 6 winner Mac Danzig has been forced to withdraw from his match-up with WEC stand-out Donald Cerrone due to a torn muscle and will be sidelined for at least the immediate future if not slightly longer. Their bout was one of the card’s most potential-laden pairings, as both men are not only polished competitors possessing entertaining in-ring approaches but had a budding rivalry due to a variety of comments exchanged through the media.

News of the cancellation was first reported by MMAWeekly where specifics were scarce in terms of the exact nature of Danzig’s injury or expected recovery time.

The 20-8-1 Danzig’s current condition means he will have been out of action for more than six months whenever he returns to the Octagon. He was last seen knocking out Joe Stevenson at UFC 124 a little less than two minutes into their bout, the fifth strike-based stoppage of the 31-year old’s career.

UPDATE: Stepping in for the injured Danzig will be Vagner Rocha, a 6-1 BJJ blackbelt making his UFC debut after appearances in Strikeforce and Bellator.

Comparably, “Cowboy” Cerrone is coming off a trio consecutive wins including back-to-back submissions of Chris Horodecki and Paul Kelly in his most recent outings.

Today’s news marks yet another instance of promotional officials having to reshuffle the UFC 131 deck, as the diminished health of scheduled participants has already affected a number of bouts including the previous headliner between Brock Lesnar and Junior dos Santos, as well as other fights involving Krzysztof Soszynski, Jesse Bongfeldt, and Dustin Poirier.