Kevin Iole is reporting that per Dana White the fight has not yet been canceled or postponed:
Fiveouncesofpain.com initially reported Friday that the bout was off because of a back injury sustained by Mir. It later corrected that to say it was a knee injury. And then MMAWeekly.com reported Mir had knee surgery.
….
“I don’t know anything about it, so I honestly couldn’t tell you anything about it,” White said of Mir’s injury and the report that the fight was off. “I’m not too worried about it now. If that were the situation, I’d know about it. I honestly don’t know right now. I haven’t talked to Frank and I haven’t talked to Lesnar and if that’s the situation, I’m not going to make any statements until I talk to everybody.”
But a source in Las Vegas close to Mir said his knee began swelling excessively last week after a workout. After an examination, Mir had arthroscopic surgery to “clean up” the knee.
If it was just a “clean up” it won’t take excessive time for recovery and it is still very realistic that the fight takes place as scheduled. I think at this point the ball is firmly in Frank’s court as he has to rest it and then see if he is able to train normally and determine if he can have a productive enough training camp for a fight of this magnitude.
[UPDATE] by Nick Thomas: Frank Mir interview at the 2009 Arnold Classic – says he hopes the fight is moved to the summer because of his knee and that he can’t train for 4-6 weeks. (video) [1:20 min mark]