Dallas Cowboys defensive end Anthony Spencer will reportedly undergo season-ending surgery on his knee this week.

The 29-year-old suffered a setback in his recovery from his injury after playing in the first game of the season against the New York Giants.

Dallas hoped that he could recover again without the need for surgery, but the injury proved too severe forcing him under the knife.

Spencer is a free agent in March and is expected to return to fitness in late January to early February, so he is unlikely to feature for the Cowboys unless they reach the Super Bowl, reports ESPN.

Dallas are 2-2 in their season after week four of the season.