Williams (quadriceps) appears to be practicing Friday, Darren Urban of the Cardinals' official site reports.
With Williams absent from the prior two practices, it appeared the Cardinals might need to lean on Elijhaa Penny as their lead runner for Sunday's game against the Giants. Williams' return to practice Friday at least gives him a shot to play, though it's still quite possible he's no better than a game-time decision. Another update will be available Friday afternoon when the Cardinals release their final injury report.