Williams had to be helped off the field after hurting his ankle at Tuesday's practice, but coach Anthony Lynn told reporters Thursday that his sprained ankle did not appear to be too serious, although he had no timetable for his return.
It was initially feared that Williams suffered a high-ankle sprain. The Los Angeles Times reported that Williams is expected to miss two weeks.
The injury to Williams, who was at Thursday's practice on crutches and wearing a walking boot, came four days after four days after former Pro Bowl cornerback Jason Verrett suffered a season-ending torn Achilles during a conditioning test.
Williams started 15 games in 2017 and had a pair of interceptions, 21 passes defensed and 54 tackles. Signed as an undrafted free agent out of Penn State by the Chargers in 2016, Williams started five of 12 games during his rookie season, registering 23 tackles and five passes defensed.