Dallas Cowboys middle linebacker Sean Lee missed Friday's practice and was ruled out for Sunday's game against the Green Bay Packers.
Lee injured his neck in the first quarter Monday is a loss at Chicago. He left the game for good in the third quarter.
Lee was optimistic Wednesday that he could "manage it the rest of the season," but discomfort returned Friday.
Lee missed two previous games with a hamstring.
His backup, Bruce Carter, is hobbled by a hamstring injury and hasn't practiced all week.