Williams will start at point guard. Pierce will be coming off the bench for the first time this season and only fourth time in his 16-year NBA career.
Williams returns to the lineup after dealing with nagging ankle injuries this season.
Pierce broke his right shooting hand less than two weeks ago and will wear a special protective glove tonight as he faces his former team for the first time.
The last time Pierce came off the bench was in February 2007, against the Nets.