Montembeault allowed five goals on 25 shots before being pulled after two periods in Saturday's 6-2 loss to Vegas.
Montembeault, who won three of four outings with a .966 save percentage going into Saturday's game, started well with a scoreless first period before it all came apart. The Golden Knights capitalized on sloppy play in front of the goalie in the second period, putting five pucks past him on 13 shots. Montreal head coach Martin St. Louis had seen enough and replaced him with Cayden Primeau to start the third period. The 28-year-old Montembeault hasn't finished the game three times in 15 starts. The Canadiens' next matchup is Tuesday at home against Columbus.