Outscored 10-4 in defeats to Minnesota and Columbus, Boston extended its winning streak against the archrival Canadiens to four games as Rolston, Bill Guerin and Joe Thornton notched third-period goals.
Rolston broke a 2-2 tie at 4:21. Sean O'Donnell did a good job keeping the puck inside the Montreal blue line before making a cross-ice pass to fellow defenseman Don Sweeney. Sweeney's flip from the left point did not reach the net, but Rolston fished the puck out of his skates and flicked it past goaltender Jose Theodore for his eighth goal.
Theodore denied P.J. Axelsson on a breakaway but gave up a weak goal to Guerin that made it 4-2. After stickhandling into the Canadiens' zone, the NHL's shot leader wristed one from above the right faceoff circle that hit the goalie's glove and dropped into the net with 8:46 to play.
With Theodore pulled for an extra attacker, Oleg Petrov scored in the final minute to get Montreal within 4-3. But Thornton, who set up Sergei Samsonov's first-period goal, fired into an empty net just 14 seconds later.
Byron Dafoe stopped 17 shots for the Bruins, who improved to 5-1