Dallas Cowboys defensive end Anthony Spencer may need microfracture surgery on his left knee.
Cowboys owner Jerry Jones broke the news during a radio spot on 105.3 FM "The Fan" in Dallas on Tuesday morning.
"It's a real setback," Jones told the station according to the team's website. "It could be out for the season."
Spencer, who was given the Cowboys' franchise tag during the offseason, underwent knee surgery at the end of July and missed the Cowboys' season opener against the Giants. He returned for Week 2's loss to Kansas City, but missed Week 3's win against St. Louis.
A 2007 first-round pick from Purdue, Spencer registered 11 sacks and 95 tackles last season as the team's 3-4 outside linebacker opposite DeMarcus Ware.