Strikeforce: "Killer Crossover" now has an official date.

Former Ultimate Fighting Championship (UFC) Heavyweight Champion Frank Mir will make his "one off" cross-promotional appearance when he steps inside the Strikeforce cage to battle the mixed martial arts (MMA) promotion's 2012 grand prix winner, Daniel Cormier.

MMAFighting.com reports that the Frank Mir vs. Daniel Cormier three-round main event attraction will take place at Chesapeake Energy Arena in Oklahoma City, Okla., on Nov. 3, 2012. Naturally, the event's main card will air live on the Showtime premium cable channel, beginning at 10 p.m. ET on fight night.

Mir, who is just one fight removed from challenging for the UFC heavyweight belt, is actually coming into the match as a significant underdog. He strung together three straight victories, including a gruesome, arm-snapping submission of Antonio Rodrigo Nogueira, to earn a date with division champion Junior dos Santos.

Sure, Mir was plugged in when Alistair Overeem failed a random pre-fight drug screening, but he was a more than respectable adversary. However, that didn't stop "Cigano" from battering him from pillar to post at UFC 146 en route to a second round technical knockout stoppage.

He'll be up against a whole new animal when he takes on Cormier, a stocky, decorated amateur wrestling champion who has improved markedly with each MMA performance.

Indeed, "DC" has looked all but unstoppable lately. He showed off an improved striking game against Jeff Monson in a smooth unanimous decision win before knocking Antonio Silva's head off and rag-dolling Josh Barnett to win the Strikeforce heavyweight grand prix.

As the competition has improved so have his performances inside the cage. And he'll look to continue that trend when he steps it up again against Mir almost exactly two months from today.

For more on the Strikeforce: "Cormier vs. Mir" (note that "Killer Crossover" moniker that was used earlier just for grins and giggles) -- event click here.