In the first round of the 2009 playoffs against the Chicago Bulls, game one proved to be tough for Allen. He ended up shooting 1–11 from the field, and the Celtics lost by two. In game 2 however, Allen nailed the game winning three-pointer at the end of regulation with two seconds left to cap off an impressive 30 point night. In Game 6, despite a Boston loss, Allen managed to score 51 points. Boston ended up winning the series in 7 Games. He reunited with former teammate and co-captain of the Seattle SuperSonics, Rashard Lewis in the Conference Semifinals, this time as opponents, however. After 4 games and a 2–2 series tie, his highest scoring game was a 22-point performance in a Game 2 victory. The Celtics went on to lose in seven games as they failed to defend their title.