James also pulled down 10 rebounds before exiting after the third quarter while Chris Bosh added 19 points and 10 boards for the Heat, who received their 2011-12 NBA Championship rings before the contest.
Former Celtic Ray Allen connected on 5-of-7 shots for 19 points off the bench in his first game with the Heat and Mario Chalmers dished off 11 assists as Miami weathered a late charge to register the victory.
Paul Pierce provided 23 points and Rajon Rondo chipped in with 20, 13 assists and seven rebounds for the Celtics, who fell despite shooting 52 percent from the floor.
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