Head coach Dan Campbell said Williams (ankle) won't practice Wednesday, Tim Twentyman of the Lions' official site reports.
Campbell downplayed Williams' injury Monday, but the ankle issue is significant enough to keep the wide receiver off the practice field as the Lions begin Week 18 prep. The coach said that the team plans to play its starters as usual against the Vikings in Sunday's regular-season finale, but injured players could get the week off to heal up in advance of the playoffs. With that in mind, Williams may be held out as a precaution even if the injury isn't especially significant.