Peter Diana/Post-Gazette

Willie Parker is listed as doubtful for Sunday's game.

Pro Bowl running back Willie Parker, who is concerned about the health of his sprained knee, did not practice today and is not expected to play against the New York Giants.

Coach Mike Tomlin said he will list Parker as doubtful. Left tackle Marvel Smith, who has not practiced the past two weeks because of back spasms, will not play against the Giants, Tomlin said. He will be replaced by Max Starks.

Also, defensive end Aaron Smith was excused from practice for personal reasons for the third day in a row, increasing the possibility he also will not play against the Giants.

"He has our complete and full support," Tomlin said. "He's going through a time right now. It's questionable whether or not he'll participate, at this time."

Parker has missed the past three games with a sprained medial collateral ligament in his left knee. He went through a full practice Wednesday, but was limited in his work yesterday.

He will be replaced in the starting lineup by Mewelde Moore.