Williams (back) is listed as active for Thursday night's game against the Raiders.
As is Keenan Allen (hamstring), though ESPN's Adam Schefter suggests that the duo will be on some sort of a "a rep count." With that in mind, Jalen Guyton and Tyron Johnson could be more involved than normal, but Williams will at least give it a go Thursday, a context that makes him a hit-or-miss fantasy lineup option in Week 15.