Paul Byron and Jake DeBrusk matched goals to open the shootout, but there were five misses before Marchand potted the victor.
Danault is stretchered off the ice. When he regained consciousness, he attempted to get back to his feet, but he collapsed after getting to his knees.
Officials called off the final 1:27 of the period, which were played at the beginning of the third period. The team said he was taken to a hospital with a head injury for further examination.?
With less than two minutes remaining in the second period, Chara one-timed a puck that sailed on him and caught Danault around the earpiece of his helmet. Pacioretty had a couple of swipes at the loose puck before bouncing it off Tuukka Rask's skate.
Marchand, Jake DeBrusk and David Krejci all scored for the Bruins, who improve to 24-10-7 on the season and are 9-0-2 in their last 11 matchups. He has seven goals and 15 assists in 43 games this season. Marchand got a step on Byron and converted a flawless pass from Patrice Bergeron. The Canadiens captain got a third goal in as many games. Nicolas Deslauriers pulled Montreal even when he picked off a pass from Chara in the neutral zone and then beat Rask at 5:45 with s flawless shot along the ice on the blocker side.
Galchenyuk took a diagonal feed from Jonathan Drouin in the right circle and beat Rask with a wrist shot under the crossbar on a power play at 8:51.
Boston managed to tie things up before second intermission, with Krejci picking up a blocked shot from McAvoy and wristing it past Price for the 3-3 deadlock.