Former UFC interim heavyweight champion Shane Carwin announced on his web site Saturday that he has suffered another back injury.
Carwin expects the injury to sideline him until next year.
“As I ramped up my training for UFC 141, my back locked up,” Carwin said. “It wasn’t like the [Brock] Lesnar fight, but my back just tightened up and I froze.
“I scheduled an MRI and the results showed that my disc in my lower back is into the nerves. My doctor gave me two options: retire and I could probably go on for a few years without surgery or I could undergo surgery and continue fighting.
For Carwin, the decision wasn't a difficult one to make.
"I have unfinished business [inside the Octagon]," he said. "The UFC had me lined up to face one of the best in the world and I am confident I have everything I need to be a champion. I am scheduling surgery and I hope to return to the Octagon by spring or summer of 2012.”
Carwin (12-2, 4-2 in UFC) suffered a previous back injury after a second-round submission loss to Lesnar during a title bout at UFC 116 in July 2010.
It was the first loss of Carwin’s professional mixed martial arts career. He would lose by unanimous decision to Junior dos Santos in his next fight on June 11 at UFC 131.
Carwin-dos Santos was a heavyweight title elimination fight. Dos Santos is scheduled to face current heavyweight champion Cain Velasquez on Nov. 12 in Anaheim, Calif.
While Carwin states he was preparing to compete at UFC 141 when his recent back injury occurred, sources with knowledge of the situation informed ESPN.com on Sunday that the promotion never made an official announcement of such a fight.
It is also not known whom Carwin would have fought at the event.
UFC 141 takes place Dec. 30 at MGM Grand Garden Arena in Las Vegas. Lesnar is scheduled to face former Strikeforce heavyweight champion Alistair Overeem in the main event.