) has learned from sources close to the promotion that Florian suffered an undisclosed injury while training for a planned matchup with Dunham and has been forced to withdraw from the bout.
The pair was expected to meet in the main event of "UFC Fight Night 23: UFC Fight for the Troops 2," which takes place Jan. 22 at Fort Hood in Killeen, Texas.
The UFC has yet to announce the change, and it's currently unknown whether a replacement opponent will be found or if the matchup will be pushed back to a later date.
Florian's manager, Malki Kawa, declined to comment on the report when contacted by MMAjunkie.com.
Both Florian and Dunham were looking to recover from recent losses.
Dunham faced former UFC lightweight champ Sean Sherk in September and was dealt the first loss of his career via close split decision. After suffering a huge gash near his right eye in the opening round of the UFC 119 fight, Dunham battled back with an impressive blend of striking from distance and a capable takedown attack. Nevertheless, Sherk was granted the decision.
Prior to the loss, the Brazilian jiu-jitsu black belt posted UFC wins over Per Eklund, Marcus Aurelio, Efrain Escudero and Tyson Griffin.
Florian, meanwhile, hoped to return to the cage for the first time since suffering a unanimous-decision loss to Gray Maynard at UFC 118 in August. In a fight to determine the 155-pound division's next title challenger, Florian was unable to defend against Maynard's wrestling attack and lost the fight on all three judges' cards.
The former title challenger now is just 2-2 in his past four fights, though the defeats have come at the hands of current No. 1 contender Maynard and former lightweight champion B.J. Penn.