Looks like the first UFC-Strikeforce crossover bout will have to wait.

Former UFC heavyweight champion Frank Mir had to pull out of his Nov. 3 bout with Strikeforce Grand Prix Heavyweight Champion Daniel Cormier. The bout was set to take place under the Strikeforce banner.

The MMA radio show “Sports Rage” was the first to report the news late Tuesday evening, while MMA Junkie quickly confirmed the report. MMA Junkie also indicated that Mir appears to have suffered a knee injury.

Cormier, a former All-American wrestler at Oklahoma State University, looked forward to facing a high-level opponent in front of a Oklahoma City, Oklahoma crowd at the Chesapeake Energy Center.

The bout may now potentially be headlined by the Strikeforce middleweight title fight between champion Luke Rockhold and challenger Lorenz Larkin.

As of early Wednesday afternoon, neither UFC nor Strikeforce officials have commented whether or not “DC” would have a new opponent for the card.

Mir last fought at UFC 146, getting TKO’ed by UFC heavyweight champ Junior dos Santos in the second round. Mir was a replacement for Alistair Overeem, who was suspended by the Nevada State Athletic Commission prior to the bout due to elevated testosterone levels.

Meanwhile, Cormier stands at a perfect 10-0 as a professional mixed martial artist, most recently winning a lop-sided decision over another former UFC heavyweight champion, Josh Barnett, in May.