Former UFC heavyweight champion Frank Mir is the latest fighter to go down with an injury.

Mir, who suffered an undisclosed knee injury according to a report by MMAjunkie.com, will not face Daniel Cormier in November at Strikeforce: Cormier vs. Mir.

Mir was scheduled to become the first active UFC fighter to compete for Strikeforce. Nothing has been confirmed by Zuffa, the UFC or Strikeforce.

Cormier is expected to join the ranks of the UFC’s heavyweight division after fighting once more for Strikeforce. A replacement for Mir is unknown at this time.