Patrice Bergeron tallied a goal and two assists as the Boston Bruins won their fifth straight road playoff game by beating the St Louis Blues 7-2 in game three of the Stanley Cup finals.

Bergeron, Torey Krug, Marcus Johansson, and David Pastrnak all scored on the powerplay and Tuukka Rask made 27 saves for Boston, who lead the best-of-seven NHL championship series two games to one.

Heading into Saturday’s contest, the Bruins hadn’t been getting much production in the series from their top line or their powerplay. But that all changed in game three as Bergeron’s line caught fire and the Bruins capitalized on several St Louis’ penalties in front of a crowd of 18,700.

“I can tell you as a penalty-killer in practice, it’s hard to compete against those guys,” Bruins left wing Jake DeBrusk said. “I can tell you they’re a lot of fun to watch. I have a lot of respect for the way they move the puck. They’re really good and talented players, and they find options all over the ice.”

Game four is on Monday in St Louis, where the Blues will try to avoid sinking into a 1-3 hole.

Since 1939, when the finals went to the best-of-seven format, the team that wins game three for a 2-1 lead has gone on to win the Stanley Cup 79 percent of the time.

The Blues evened the series by winning game two at the Boston Garden 3-2 on defenceman Carl Gunnarsson’s goal at 3:21 of overtime. The Bruins won game one 4-2.

Sean Kuraly, Noel Acciari and Charlie Coyle also scored for the Bruins who chased Blues rookie goaltender Jordan Binnington from the net halfway through the second period with their fifth goal of the game.

Binnington, who allowed three goals on four shots at one stage and looked shaky from the opening puck drop, was replaced by Jake Allen who made his first appearance of the playoffs.

Ivan Barbashev and Colton Parayko scored goals and Allen finished with three saves on four shots for the Blues, who are in the finals for the first time in 49 years.

Binnington stopped just 14 of 19 shots. He didn’t get much help from his teammates, especially the defence as Jason Bouwmeester was on the ice for three of the first four Bruin goals.

“Five goals, I’d seen enough,” said St Louis head coach Craig Berube. “But my confidence level in him is really high.”