Williams (thigh) has been ruled out for Sunday's game against Pittsburgh, Tim Twentyman of the Lions' official site reports.
Williams still hasn't returned to practice and now will miss a second straight game on the other side of a Week 9 bye. His absence could leave a few more carries for D'Andre Swift, who has done most of his damage through the air this year while averaging just 3.2 YPC. Godwin Igwebuike and Jermar Jefferson both got some playing time off the bench in a 44-6 loss to the Eagles in Week 8, but only after Swift had played 96 percent of offensive snaps through the first three quarters of the blowout.