BEDFORD, Mass.— The Boston Bruins thought they excised the specter of last season’s postseason collapse when they finished off the Philadelphia Flyers in the Eastern Conference semifinals this year.

Yet here they are again, one round later, trying to turn back another comeback.

The Bruins will play the Tampa Bay Lightning in Game 7 of the conference finals on Friday night, with the winner earning a chance to play the Vancouver Canucks for the Stanley Cup. But Boston could have avoided a winner-take-all predicament if it had merely protected a three-goal lead in Game 4; scored more than one power-play goal a week in the playoffs; or kept Tampa Bay from scoring, as often as not, in the first 90 seconds of the game.

“We’ve got a Game 7, it’s at home, and we’re one game away from the Stanley Cup finals. Why shouldn’t we be excited?” coach Claude Julien said Thursday after stepping off the team charter.