Noah Dobson scored twice for Montreal (32-17-9), which has points in six consecutive games (4-0-2). Montembeault made 22 saves.
Lee, the Islanders captain playing in his 900th game, tied it 3-3 with 1:41 remaining in the third period when Bo Horvat’s shot went in off him while he was set up in front of the crease.
“That was disappointing, obviously,” Dobson said. “We don’t want to be giving away points but we can clean up some things.”
Dobson put the Canadiens up 1-0 at 12:11 of the first period. He took a cross-ice pass from Lane Hutson in the neutral zone before driving in and scoring on a wrist shot under Sorokin’s glove from the left face-off circle.
Dobson scored his second straight against his former team on a power play at 10:06 of the second period to make it 2-0 with a slap shot from the point on a pass from Alexandre Texier.
Alex Newhook got the secondary assist on Dobson’s second goal in his return after missing 40 games because of a broken ankle.
Schaefer cut it to 2-1 with a power-play goal at 17:56. He took a pass from Mathew Barzal at the top of the left face-off circle and scored on a low wrist shot from the top of the slot.
Schaefer tied it 2-2 at 18:51 with a highlight-reel goal. The 18-year-old defenseman carried the puck down the left side, cutting behind the net and skating back toward the right point before curling back to his left and scoring on a wrist shot from the top of the right face-off circle.
“I didn’t think we shot enough early on in the game,” Schaefer said. “And then I was gaining speed, went around the net, and I took the ice they gave me and cut to the middle. I knew he was going to put his stick in so I wanted to get under that stick and just throw one at the middle. When you put pucks on the net, great things happen.”