Trevor Ariza scored 27 points capped by a 3-pointer that highlighted a fourth-quarter run as the Wizards rallied for a 106-99 victory Saturday.
After Jeff Green's layup with 6:14 left gave the Celtics a 92-84 lead, they went nearly six minutes without a field goal.
Meanwhile, the Wizards were going on a 14-1 run that Ariza started with a jumper from the right corner. John Wall had five of his 20 points in the surge, which was interrupted only by a free throw by Jared Sullinger that gave Boston a 93-91 lead with 3:39 remaining.
The Celtics had led 32-14 early in the second quarter. But in the last six minutes of the game, they were outscored 22-7, committed four turnovers and had two shots blocked.