Williams, who has played in 58 of the Lakers' 61 games (12-49), left his team's 107-101 victory over the Brooklyn Nets on Tuesday night after playing just under 10 minutes.
On the season, Williams is averaging 15.3 points and 2.5 assists a game.
Without him, the Lakers may rely more heavily on young guards D'Angelo Russell and Jordan Clarkson, along with veteran Kobe Bryant. Marcelo Huertas, Nick Young and Anthony Brown may also gain minutes in Williams' absence.
The veteran was examined via ultrasound on Wednesday morning by Dr. Steve Yoon of the Kerlan-Jobe Orthopaedic Clinic.