Marchand, Boston's top goal scorer in the regular season, got his first of the post-season on a pass from Patrice Bergeron. Marchand had carried the puck up the right side, passed it to Bergeron and kept going toward the net. Bergeron passed across the slot and Marchand tipped it past goalie Henrik Lundqvist from the left side of the crease.
The Bruins carried the play throughout overtime. They applied constant pressure, but couldn't score during a power play when Derek Dorsett was penalized for interference at 2:20 of overtime.
Boston nearly won in regulation, but Johnny Boychuk's shot from the right point clanged off the left post with one-tenth of a second remaining.
LOS ANGELES (AP) — Captain Dustin Brown tied it with 1:43 left and Trevor Lewis scored the tiebreaking power-play goal 22 seconds later, propelling the Kings to a stunning victory and a 2-0 series lead.
Brown scored during a 5-on-3 advantage and Lewis provided the winner on a loose puck with 1:21 left, sending Staples Center into shocked celebration. The defending Stanley Cup champions won their 12th straight home game since March and their sixth straight post-season game.
Marc-Edouard Vlasic scored his first career playoff goal with 11:04 to play for the Sharks, who were doomed by two late penalties after rallying from an early two-goal deficit.
Jonathan Quick made 28 saves for the Kings, and Antti Niemi stopped 27 shots for the Sharks.
Game 3 is Saturday night at the Shark Tank.