St. Louis' first moments behind the Canadiens bench did not go exactly as planned, as the team fell behind by a pair of goals early to start the game, before settling down.
Joe Snively scored his first of the season at 5:04 before Connor McMichael doubled the lead just 20 seconds later to make it 2-0.
The Capitals held a slim 11-10 edge in shots through the game's opening 20.
Washington added to its lead to start the middle frame, as Carl Hagelin made it 3-0 at 3:40. That goal sparked the busy 96-second sequence that followed.
Rem Pitlick got the Canadiens on the board with his ninth of the season at 4:09, before Snively's second of the night restored the Capitals' three-goal lead just 69 seconds later.