The Celtics haven’t been so good at doing themselves favors lately. That’s why last night could be considered rare. Faced with a currently sixth-seeded Atlanta team one rung up the playoff ladder, the Celtics cut the distance to 11⁄2 games with their 118-107 win over the Hawks. On a night when the typically well-coiffed Rajon Rondo reappeared from his post-surgical rehabilitation on the Celtics bench, the team scored like he was once again in charge. Paul Pierce sprung for his third triple-double of the season with 20 points, 10 assists and 10 rebounds, and was only one in a Hollywood-sized cast of unleashed scorers. Jason Terry came within one basket of his high as a Celtic with a 24-point performance that included five 3-pointers, four of them in the second quarter. Jeff Green, fresh off his game-winning drive Wednesday night in Cleveland, built momentum with 27 points on 11-for-20 shooting, including three 3-pointers. And Shavlik Randolph, who has shown the coaching staff glimpses of his instinct for getting rebounds, offered his strongest sample yet with a game-high 13 boards. Lost in the wash was the return of Courtney Lee following a three-game absence to a left ankle sprain. He came off the bench, lasted six minutes and hit two free throws. Last night’s offensive explosion was a long time coming, considering Wednesday’s pained win over the Cavaliers and the five-game losing streak that preceded it. Pierce, coming off a seven-turnover night in Cleveland, only forked the ball over once in 38 minutes against the Hawks.