Williams, averaging 17.2 points and 6.3 assists, missed five games in early March with the same injury.
Williams played in the Bucks' last game, a loss to the Pacers Friday night. He had two points and eight assists in 18 minutes.
Ramon Sessions, a rookie from Nevada, got his first career start in Williams' place.
Williams is one of several injured Bucks. Center Jake Voskuhl (left ankle sprain), guard Charlie Bell (MCL, right knee) and Yi Jianlian (sprained left knee) were inactive and not with the team Sunday.