BOSTON — P.K. Subban scored his second goal of the game at 4:17 of the second overtime to give the Montreal Canadiens a 4-3 victory over the Boston Bruins on Thursday night in Game 1 of the Eastern Conference semifinals.

The goal came 7 seconds into the Canadiens’ second power play of overtime. Fans pelted the ice with cups and giveaway towels as the players filed off of the ice.

Carey Price stopped 48 shots for Montreal. Rene Bourque and Francis Bouillon also scored for the Canadiens, who blew 2-0 and 3-2 leads in the third period.

Tuukka Rask made 29 saves for the Bruins, who finished the regular season with the best record in the NHL but lost home-ice advantage in the series.

The Bruins, who never led in the game, outshot the Canadiens 14-6 in the third period and twice rallied to tie it. The Canadiens picked up a questionable power play at the end of the first overtime and failed to score, but there was little doubt about the call when Matt Bartkowski was sent off for taking down Dale Weise in the crease to keep him from getting to a loose puck.

Montreal won the ensuing faceoff and worked the puck around to Subban, who slapped it past Rask to end the game.

Game 2 is Saturday in Boston.

The 34th postseason series between the two Original Six rivals began without much of the intensity of past matchups. Only after the Bruins fell behind 2-0 did they seem to realize that they were in trouble.

When Josh Gorges was sent off for holding 14 minutes into the second period — Boston’s first power play of the game — the Bruins repeatedly tested Price, holding the possession in the Canadiens’ zone virtually the whole 2 minutes and getting several good scoring chances.

Dougie Hamilton hit the crossbar and Jarome Iginla missed a wide-open net, leaving Montreal’s 2-0 lead intact heading into the third period. But no longer were the Bruins being pushed around.

Reilly Smith wristed one past a screened Price with less than 3 minutes gone in the third period to make it a one-goal game. Shortly after another unsuccessful power play, Milan Lucic muscled his way through the defense and passed it to Torey Krug for a slap shot that went past Price’s left skate.

Bouillon gave Montreal the lead again, finishing off a scramble in front of the net. But with 2 minutes left, the Bruins won a faceoff in the Canadiens’ end, kept the puck in and then worked it around to Boychuk, who slapped it past Price to send the game into overtime.

Montreal took a 2-0 lead after two periods on a first-period power-play goal by Subban and Bourque’s score 3:36 into the second. Bourque had three goals in Montreal’s first-round sweep of Tampa Bay, but it was his first point in nine career playoff games against the Bruins.

NOTES: Montreal won 24 of the previous 33 playoff series, but the Bruins have won seven of the last 11 and two in a row. In 2011, on their way to the Stanley Cup championship, Boston beat Montreal in seven games in the first round after losing the first two at home. … Montreal won three of four in the regular season. … Lars Eller has a point in all five Montreal playoff games so far.