Tkachuk extended the lead to 3-0 at 8:02, redirecting DeBrincat's shot in front for another power-play goal.
"I feel like we have so many different looks, it's hard to defend all of them," DeBrincat said of the power play. "If we keep moving it around quickly like that, keep putting pucks on net and getting retrievals, I think we're going to score a lot."
At the time of the goal, Ottawa was outshooting Montreal 12-0 in the second.
"We liked our first period, no doubt," Dvorak said. "Second period, we were just on the penalty kill the whole period, so it's tough when you're doing that."
Dach made it 3-1 at 8:05 of the third period with a one-timer from the low slot off a backhand centering pass from Jake Evans from below the goal line.
"Our discipline kind of slipped away in the second," said Dach, who was called for three penalties in the second period. "I felt like 5-on-5 we were playing our game, we had control. … I obviously take ownership with the penalties I took tonight. The timing of them wasn't the best."