Erik Christensen had two goals and an assist, and Marc-Andre Fleury stopped 31 shots as the Penguins won their fourth consecutive game and ninth out of 11. Pittsburgh has 100 points, two more than idle New Jersey and second in the conference only to the Buffalo Sabres.
With the loss, the Bruins were officially eliminated from playoff contention.
Phil Kessel and Brandon Bochenski each had a goal and an assist for Boston, which took a 1-0 lead just 45 seconds into the game but fell behind 2-1 before the midpoint of the first period. Tim Thomas stopped 22 shots for his fifth consecutive loss and the Bruins lost for the sixth time in seven games.
Kessel tied it 2-2 with 10:56 gone in the game when he came from behind the net, flipped the puck into the air and then batted it past Fleury. But Pittsburgh took the lead for good 31 seconds later when Crosby fed Christensen as he streaked down the left side; he wristed a shot through Thomas' pads.
The Penguins made it 4-2 with 8:30 left when Michel Ouellet dug the puck out and from behind the goal line passed it across the crease to Evgeni Malkin. It was Malkin's 33rd goal of the season and fifth against Boston, but just his second in the last 10 games.
Notes: Thomas was named the Bruins' "Seventh Man" before the game. ... Pittsburgh had lost five straight in Boston and nine of 10 to the Bruins. ... Ouellet had a pair of assists for the Penguins.