Todd Duffee has pulled out of his heavyweight bout against Paul Buentello at UFC 107 on Dec. 12 in Memphis, Tenn., due to an injury.

“(Withdrawing) was one of the hardest decisions I’ve had to make,” said Duffee, who would not disclose the nature of his injury.

Duffee, 23, burst onto the UFC scene with a record-setting seven-second knockout of Tim Hague at UFC 102 in August. The undefeated heavyweight, who recently relocated to Las Vegas to attend the University of Nevada-Las Vegas, hopes to be back in action by early 2010.

“It was a fight I was really looking forward to,” Buentello told Sherdog.com on Tuesday. “We really matched up well.”

Mike Russow and Stefan Struve have been presented as two potential replacements for Duffee, said Buentello.

Buentello will make his UFC return on Dec. 12 after nearly four years away from the Octagon. The 35-year-old heavyweight has rattled off an impressive 12-2 record over the past six years with his only defeats coming in title matches against Andrei Arlovski (in the UFC) and Alistair Overeem (in Strikeforce.)

Russow, 33, earned a unanimous decision victory over Justin McCully in his UFC debut in August. Russow, a Chicago police officer by day, has tallied 12 wins in 13 professional bouts.

The 21-year-old Struve has shown quite a bit of promise in his young MMA career. The towering 6-foot-11 Dutchman submitted Chase Gormley with a first-round triangle choke at UFC 104 on Oct. 24 to earn “Submission of the Night” honors by the promotion.