Paul Pierce found out the hard way what can happen when you get in the way of LeBron James.

The Celtics captain left Boston's season opener with the Miami Heat on Tuesday night in Boston with what TNT reported as back spasms. Pierce appeared to suffer the injury while trying to slow down James on a fast break. Replays suggested that the play might have been a charge, but Pierce was whistled for a blocking foul.

TNT's Craig Sager reported that Celtics head athletic trainger Ed Lacerte said that Pierce was suffering from back spasms and was heading to the locker room to have it worked on by a massage therapist.

The Celtics were leading the Heat, 58-45 with 3:53 to play in the third quarter when Pierce was replaced by Marquis Daniels.