by Ken Pishna – MMAWeekly.com
Todd Duffee has been forced to withdraw from his planned UFC 107 bout with Paul Buentello.

Sherdog.com first announced the withdrawal on Tuesday. MMAWeekly.com has independently confirmed that Duffee is out due to a back injury.

Duffee has had somewhat of a meteoric rise, making his professional mixed martial arts debut just two years prior to signing on with the Ultimate Fighting Championship. He made an immediate splash, knocking out Tim Hague in an Octagon record time of seven seconds.

Buentello is expected to remain on the Memphis, Tenn., fight card. Sherdog.com mentioned Stefan Struve and Mike Russow as leading candidates to replace Duffee, but it remains unclear if the fight has yet been offered to either.

A UFC lightweight championship bout between titleholder B.J. Penn and challenger Diego Sanchez headlines on Dec. 12 at UFC 107.