Goaltender Robin Lehner made 33 saves and his Ottawa teammates made the most of their opportunities.
Andrei Markov scored the first goal of the game during a first-period play.
But Bobby Ryan tied it at 1-1 28 seconds later, and Ottawa took control with two goals in 37 second-period seconds. Defencemen Mark Methot and Mark Borowiecki took advantage of confusion in the defensive zone and screens in front of Carey Price.
Kyle Turris added an empty-netter.
robin Lehner made 33 saves, 25 over the final 40 minutes.
The Senators had 23 shots on Carey Price.
Senators hold the fort
Ottawa maintained its lead, and Kyle Turris added an empty-netter.
Robin Lehner's excellence snuffed any hope of a CH comeback.
Two quick ones
Ottawa defencemen scored twice in 37 seconds to give the Senbators the lead.
Andrei Markov cleared a rebound directly to Mark Methot, who blasted it past Carey Price.
Then Mark Borowiecki scored the first of his NHL career, and the Canadiens were shellshocked.
Robin Lehner made 14 saves in the second period.
Price was beaten twice on six shots.
Barely enough time to crack a beer.
That's how long the Canadiens' lead lasted.
After Andrei Markov blasted one past Robin Lehner on a beautifully executed power play, Bobby Ryan used a Kyle Turris screen to fire one past Carey Price.
Canadiens outshot the Senators 9-7.
They played back-to-back exhibition games in September, but the Thursday evening dance at Canadian Tire Place is the first REAL hockey game between the Canadiens and Senators since the Eastern Conference quarter-final series last spring.
And we all remember how that ended: the Senators celebrating a five-game series win after dealing the home team a 6-1 pasting at the Bell Centre.
There have been some changes since that bitterly-fought series, which included the Eric Gryba head shot that knocked Lars Eller out of the playoffs in Game 1 and a line brawl in Game 3.
Daniel F. Alfredsson is no longer a Senator. George Parros is a Canadien.
The rivalry is not as intense as Montreal-Boston or the Battle of Ontario. But the Canadiens and Senators could find themselves in a tight, season-long battle for an Eastern Conference playoff berth.
Michel Therrien has shuffled his forward lines again: Mac Pacioretty joins Tomas Plekanec and Brian Gionta, Lars Eller is reunited with Brendan Gallagher and Alex Galchenyuk, David Desharnais returns to the lineup between Michaëel Bournival and Rene Bourque, Travis Moen is back and will play with Ryan White and George Parros.