Undefeated British submission savant, Paul Sass, was recently injured in training and has been forced out of his upcoming lightweight fight against Evan Dunham at UFC on Fox 2, which is scheduled to take place at the United Center in Chicago, Ill., on Jan. 28, 2012.

Ultimate Fighting Championship (UFC) just shared the bad news via its official Twitter.com account; however, it has already tapped Nik Lentz to replace Sass against Dunham.

Lentz was just in action at UFC 140: "Jones vs. Machida" earlier this month, dropping a close unanimous decision to Mark Bocek. Prior to the loss, "The Carney" had recorded five wins inside the Octagon, as well as a "No Contest" and a draw.

He'll look to get back in the win column against perhaps his toughest 155-pound test to date against Dunham in a fight that will take place on the under card.

Dunham (12-2) rocketed to the top of the lightweight buzz list with wins over Efrain Escudero and Tyson Griffin; however, a close split decision loss to Sean Sherk, followed by a first-round ass-whooping at the hands of Melvin Guillard, sent the talented Oregon native to the back of the line.

He quickly rebounded with a lopsided unanimous decision win over Shamar Bailey at UFC Fight Night 25 back in September.

UFC on FOX 2 will headlined by a 205-pound showdown pitting former light heavyweight champion "Suga" Rashad Evans against "Wonderful" undefeated contender Phil Davis. In the co-featured fight of the night, Chael Sonnen vs. Mark Munoz will collide in a middleweight match up that will likely determine the division's next number one contender.

To check out the latest UFC on Fox 2: "Evans vs. Davis" fight card and rumors click here.