On his 30th birthday, James was ruled out about 90 minutes before Tuesday night's game.
Cleveland forward Shawn Marion also is out with a left ankle sprain.
James' status is day to day. Coach David Blatt says that ''obviously, we want to get him right.''
James also was held out of Cleveland's Dec. 11 game at Oklahoma City with soreness in the knee.
James ranks second in the NBA in scoring with 25.2 points per game. He is tied for sixth with 7.6 assists.