The Celtics announced that head coach Jim O'Brien is resigning, effective immediately. According to a league and a team source, O'Brien's decision came after a major argument over personnel and playing time issues with director of basketball operations Danny Ainge.
Assistant coach John Carroll is expected to take over as interim head coach.
Until today, O'Brien was one of only two Eastern Conference coaches still with the same team he coached last season. O'Brien went 139-119 as the Celtics head coach since taking over after Rick Pitino resigned on Jan. 8, 2001.
The Celtics, who are 22-24 and in sixth place in the Eastern Conference, have undergone many changes on the court this season, as recent fixtures such as Antoine Walker and Eric Williams were traded.