A frantic fourth quarter rally by the Celtics fell short last night in Philadelphia as the 76er defeated Boston 99-97. Julius Erving led the effort with 28 points as the 76ers take a 2-1 lead in the National Basketball playoff semi-final series.

Boston possessed a 47-45 halftime lead as rookie sensation Larry Bird knocked home 10 points and pulled down 11 rebounds. Bird's three point field goal with 16 seconds remaining in the half propelled the Celtics into the locker room with the two point edge.

The 76ers, trailing 60-59, outscored the Celtics 18-8 in a third period eruption to give Billy Cunningham's team a 78-66 lead at the end of the third quarter.

The Celtics could not stop Erving during the stretch as he swished home 12 points during the comeback.

Explosion

After increasing their lead to 88-74 midway in the final quarter the Celtics finally caught fire as Bird sunk his third three point field goal of the night to narrow the margin to 99-97 with only 19 seconds remaining.

The Celtics got the ball back but could not convert as a forced pass inside to Dave Cowens went astray. The 76ers pounced on the loose ball and ran out the remaining second for the victory.

Veteran guard Lionel Hollins supplemented Erving's fine performance by chipping in 16 points. Darryl Dawkins and Maurice Cheeks added 14 each in the victory effort.

Bird Power

Bird paced the Celtics once again from his forward spot with 22 points while Nate Archibaled dropped in 19 and Cedrick Maxwell added 17 in the losing cause.

Key Contest

The Celtics now must even the series tomorrow night at the Spectrum or face possible elimination when they return home to the Garden for the fifth contest on Sunday afternoon.