Ken Linseman had three goals and two assists in the last two periods as the Boston Bruins erased a 4-1 deficit to overtake the Montreal Canadiens, 7-6, last night in Boston and force their NHL playoff series to a decisive fifth game.

The series, tied at two games all, will de decided Tuesday in Montreal. Boston, loser of 15 straight playoff series against the Canadiens, last defeated Montreal in 1943.

Linseman capped the comeback with the winning goal at 13:12 of the third period against one of the NHL's best teams at protecting a lead.

He took a pass in center ice from Terry O'Reilly and sped up the right side and around defenseman Tom Kurvers. He skated behind the net to the other side and, still behind the goal, knocked the puck off the right leg of defenseman Larry Robinson and past goalie Steve Penney.

Linseman had tied the score for Boston, 6-6, with his second goal of the second period, in which he also picked up two assists.

The four points in a single period tied an NHL playoff record shared by five other players.

Montreal lost defenseman Chris Chelios with a sprained right knee at 3:24 of the second period with a 4-1 lead. "The loss of Chelios is one part and the defensemen started to play a little softer," Montreal Coach Jacques Lemaire said, explaining Montreal's lapse.