Seguin pushed the score to 4-1 with another power-play goal at 8:59 after being left open with enough space on the right side to beat Swayman with a wrist shot.

Brazeau cut the score to 4-2 at 10:41 on the power play, finishing off Trent Frederic’s wraparound attempt.

“When everyone plays the right way, usually everyone enjoys success and benefits from it,” Bruins captain Brad Marchand said. “We’re kind of sitting around it, and it will come. But we as leaders and older guys have to be better and we have to set the pace and lead by example.”

The Bruins outscored the Stars 10-7 in the third period, but Roope Hintz scored an empty net goal for Dallas at 5:58 for the 5-2 final.

“When you’re trying to hold onto a lead, it’s hard because the other team takes everything they have,” DeSmith said. “Not that we sat back, but we played a little more carefully and calculatedly. So I thought they were a little desperate and they brought it in (the third) period.”

NOTES: DeBoer won his 618th game in the NHL, moving into sole possession of 21st place on the all-time list and breaking a tie with Bruce Boudreau and Jacques Lemaire. … Robertson scored his 137th goal, the second most by a Stars/Minnesota North Stars player in 300 games, behind Dino Ciccarelli (158). … It was also Hintz’s 400th NHL game. … Dallas had gone 2-for-21 on the power play through its first seven games before going 3-for-5 on Thursday. … The Stars had also gone six games without allowing a power-play goal — leading the League at 95.5 percent on the penalty kick — before allowing Brazeau’s goal. … Pastrnak scored his 78th opening goal, the most of any player from his debut season in 2014-15. … Marchand has not scored a goal in eight games this season. It is his longest opening season drought since 2010/11, when it took nine games to score.