Thomas Greiss made 33 saves, and Adam Pelech scored for New York (41-22-7), which has won four of its past five games and remained two points behind the Washington Capitals for first place in the Metropolitan Division. Washington defeated the Philadelphia Flyers 5-2 on Thursday.
"We can't control anything outside of ourselves," Lee said. "The scoreboard watching is always there; you always see what's going on, but all we can worry about is us and what we have to do."
WATCH: [All Canadiens vs. Islanders highlights]
Jordie Benn scored, and Carey Price made 36 saves for Montreal (37-27-7), which is tied with the Columbus Blue Jackets for the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
"I thought the crowd was crazy; the building was rocking," Price said. "We played a team that looked like they're ready for the playoffs."
Lee scored his 25th goal of the season when Mathew Barzal won a puck battle against Canadiens forward Max Domi at the Islanders blue line and skated up the right side on a 2-on-1 with Lee, who received Barzal's cross-ice pass and scored on a wrist shot from low in the left face-off circle to make it 2-1.
"These are the tight games you've got to have," Lee said. "You just try to keep winning, keep stacking them on. Obviously this is a team that's doing the same playoff push that we are, so it's going to be tight the rest of the way.
"I think it doubles down the importance a little bit. But you start getting to single-digit games left, they're all huge."
Pelech made it 1-0 at 1:20 of the second period. Price made an initial save on Brock Nelson's shot from the right circle, but the rebound trickled to the slot to Pelech, who scored on a wrist shot.
