Lucic gathered a bouncing puck in the slot with less than 3 minutes left and launched a turnaround wrist shot past a startled Brian Boucher to break a 2-2 tie and boost the Bruins into a commanding position after two games of their series with the Flyers.
Miroslav Satan added a goal and an assist and Johnny Boychuk added a marker for the Bruins while Tuukka Rask stopped 24-of-26 shots.
Danny Briere had a goal and an assist while Mike Richards chipped in with a tally and Boucher made 24 saves in Philadelphia's loss.
The Flyers will now look to regroup at home. Philadelphia will host Games 3 and 4 starting Wednesday after playing the first two games on the road.