Lowry was 9 for 14 from the field, including 5 for 8 from 3-point range, and added five assists and four rebounds as Toronto led the entire way in its third straight victory.
Isaiah Thomas scored 20 points for Boston, who matched a season worst with its fourth straight loss. Even Turner added 12 points in the Celtics’ fifth loss in six games.
The Raptors, playing their fourth game in five nights, built up a big lead early, let Boston back in the game and then pulled away with a 14-2 run over the first five minutes of the fourth quarter. Lowry had 10 points during that stretch, punctuating the spurt with back-to-back 3s.