Sean Kuraly of the Boston Bruins celebrates his third-period goal against the St. Louis Blues on Monday in Boston. Photo: VCG

Sean Kuraly scored the game winner ­early in the third as the Boston Bruins rallied with four unanswered goals to beat the St Louis Blues 4-2 in the opening game of the Stanley Cup finals.

After a slow start Monday, the Bruins picked up where they left off, shaking off the rust of a 10-day break to win their eighth consecutive game in the postseason.

Kuraly's third tally of the playoffs came 5:21 into the final period to break the deadlock and cap a four-goal scoring burst by the Bruins, who fell behind 2-0 early in the second.

Boston forward Noel Acciari made a spinning pass across the crease that ­Kuraly managed to kick from his skate to his stick before slamming it home.

"I am just trying to play hard. I am happy it went in," said Kuraly. "We are going to have to keep getting better. This team is not going anywhere."

Game 2 is Wednesday in Boston.

The Blues are seeking to claim their first-ever championship, while the Bruins are gunning for their first title since 2011.

Defenseman Connor Clifton, Charlie McAvoy on the powerplay and Brad Marchand, with an empty netter, also scored for the Bruins, who are playing 

in the finals for the third time this decade.

The Bruins got scoring from unlikely places with their fourth line leading the offensive charge and the defence chipping in with two helpers. Kuraly, who plays on the fourth line, also had goal and an assist in game seven of the first round of the playoffs.

"This is what they do. They can skate and they play simple hockey," said Bruins coach Bruce Cassidy of Kuraly and the fourth line. 

"For us, being off as long as we were we can't get drawn into fancy plays. They are always going to play same way - a straight line game - and they got ­rewarded."

Finnish veteran Tuukka Rask easily won the goaltending battle with Blues rookie netminder Jordan Binnington by making 18 saves in front of a crowd of 17,500 at the Boston Garden.

"We've been real disciplined all playoffs. We weren't tonight with five penalties. We got to be much better," said Blues coach Craig Berube.

Kuraly also assisted on the first Bruins goal of the game by Clifton to cut the Blues lead to 2-1.