Williams (ankle) has been ruled out for Sunday's matchup against Miami, Matt Maiocco of NBC Sports Bay Area reports.
Williams' upcoming absence doesn't come as a surprise, as he remains unable to practice. Head coach Kyle Shanahan indicated last week that the All-Pro left tackle's recovery has been slower than the team originally expected, and it's unclear when Williams may be able to return this season, if at all. Jaylon Moore started each of the past four weeks while Williams has been sidelined and presumably will do so again Sunday.