BOSTON (AP) _ Larry Bird, disregarding a painful right elbow, shed his protective bandage at halftime and scored 30 of his 42 points after the intermission Tuesday night, leading the Boston Celtics to a 121-114 victory over the Detroit Pistons and a 2-0 lead in their National Basketball Association playoff series.

The Celtics, who rolled to a 133-99 victory in the opener Sunday, withstood repeated challenges by the Pistons in the fourth period to take a commanding lead in the best-of-seven series, which moves to Detroit Thursday.

Danny Ainge had 25 points, Kevin McHale 20 and Robert Parish 14 in helping the Celtics hold off a recharged Detroit offense.

The Pistons were led by Isiah Thomas with 28 points, Kelly Tripucka with 24, Dan Roundfield with 22 and Bill Laimbeer with 15, but came up short.

The Pistons surged to an early lead on the shooting of Tripucka and Roundfield but the Celtics fought back, pulling into a tie on four occasions before Detroit edged in front 36-32 at the end of the first period.

Boston outscored Detroit 27-17 in the second period for a 59-53 lead at the half.

The Pistons regained the lead briefly, 66-65, early in the third quarter but Bird got hot and scored 13 points in sparking Boston to an 86-81 advantage heading into the final period.

The Celtics widened the lead to 10 points early in the final period, but the Pistons pulled to within two points four times before Bird became a one- man gang.

Bird, who is suffering from bursitis and apparent loose bone chips in his right elbow, scored 17 points in the fourth period, including 12 in the last 61/2 minutes for a career playoff high of 42 points.