IRVING, Texas -- Dallas Cowboys defensive end Anthony Spencer is listed as doubtful for Sunday's game against the New York Giants with a knee injury, but Spencer is thinking more about the big picture than the first game of the season.

"I've got to listen to my body, and right now it's saying, 'I'm not ready,' but who knows on Sunday?" said Spencer, who has missed six games in six seasons.

Spencer had surgery on July 25 and always felt he would be able to play against the Giants. However, he had a setback last weekend when his left knee swelled after running, and he was unable to practice this week. Spencer is coming off his first Pro Bowl season after posting a career-high 11 sacks.

"I want to make sure I'm good for the whole season," Spencer said. "That's kind of the same thing last year with my pec. If I tried to come back too early it would've put me out longer than I would've been out. I was out for two weeks, so if I came back I could've tore it completely and then I would've been out. I don't want to do anything that's going to jeopardize the season."

The Cowboys are thin along the defensive line but will re-sign Jerome Long on Saturday and are expected to put Ben Bass on injured reserve.

Bass dislocated his left shoulder in Thursday's practice and is out for the Giants game.

"I love playing football and I try to be out there as much as possible," Spencer said, "but at the same time I don't want to push it and hurt myself, which I have a habit of doing from time to time."

Running back Lance Dunbar (foot) and safety Danny McCray (hamstring) have been ruled out. Dunbar and McCray expect to be back Sept. 15 at Kansas City. Guard Ronald Leary (knee) is probable and is expected to make the first start of his career.