Fightline.com was able to confirm the news and learn that Mir suffered a knee injury in training which has forced surgery.

He will be out for the next four to six weeks while he recovers.

No word yet on a replacement match up, but one would assume that the fight will be postponed to allow the two champions to unify the heavyweight title.

Fightline.com will be following the story closely and will keep you updated with the latest as soon as more details become available.