Williams, who practiced each day last week, missed Saturday's preseason loss to the Tampa Bay Buccaneers. He was previously listed with a lower back injury.
Wide receiver Sammy Watkins, who missed Saturday's loss with a rib injury, was in uniform for the start of practice and took part in warm-up drills. Since the majority of practice drills are closed to the media after training camp, it's unclear how much Watkins participated in Monday's practice.
Meanwhile, tight ends Lee Smith and Dominique Jones (unknown), safety Jonathan Meeks (neck), and cornerback Mario Butler (ankle) all were out of practice. Smith and Jones both played in Saturday's game.