In the latest of a series of UFC fight cancellations, heavyweight prospect Todd Duffee has withdrawn from his scheduled UFC 107 bout against Paul “The Headhunter” Buentello due to an undisclosed injury. Buentello will still compete on the card and will likely face Stefan “Skyscraper” Struve or Mike Russow.

While he did not reveal the nature of his injury, Duffee expressed disappointment at having to withdraw from the fight and plans to be ready for a return to action in the first quarter of 2010.

Duffee (5-0-0) exploded onto the scene with a seven-second KO of Tim Hague at UFC 102. He has won all five of his fights to date by knockout and also holds a second-round stoppage win over former PRIDE and UFC competitor Assuerio Silva. A victory over Buentello and another top contender would have vaulted Duffee into consideration for a title shot at some point in 2010.

Buentello (27-10-0) has only gone the distance twice in his entire career and has lost just two times in his last 14 fights. Both losses – against Andrei Arlovski at UFC 55 and Alistair Overeem in Strikeforce – came in title fights. He most recently stopped Russian prospect Kirill Sidelnikov and went 2-0 in the short-lived Affliction promotion.

Replacement opponents for Buentello include Dutch giant Stefan “Skyscraper” Struve and Chicago police officer Mike Russow.

Struve (18-3-0) has won two of his three fights inside the Octagon and picked up a big victory at UFC 104 when he submitted undefeated wrestling standout Chase Gormley. At 6’11”, the 21-year-old Struve is one of the tallest fighters in all of MMA and he is surprisingly agile for his size.

Russow (12-1-0, 1 NC) has won eight straight fights since his controversial bout with Sergei Kharitonov at PRIDE 33 in 2007, in which Russow clearly tapped out to an armbar but later claimed that he hadn’t. He holds wins over Roman Zentsov, Jason Guida and, most recently at UFC 102, Justin McCully.

An official announcement regarding Buentello’s replacement opponent is expected in the coming weeks.

Also on the card, Jon Fitch will take on Mike Pierce in welterweight action.

Fitch (20-3-0, 1 NC) was first set to face Ricardo “Big Dog” Almeida and later Thiago “Pitbull” Alves in a rematch, but both withdrew due to injury.

Likewise, Pierce was initially matched against Josh Koscheck, but Koscheck will now take on Anthony “Rumble” Johnson at UFC 106.

Despite the changes, UFC 107: “Penn vs Sanchez” is still poised to be a solid event for the UFC as they travel to Memphis, Tennessee on December 12th.