The Canadiens were very opportunistic and the Ottawa Senators not at all in a 4-1 road victory for Montreal on Tuesday night.

Marc-André Bergeron and Andrei Kostitsyn each had a goal and an assist, with Mike Cammalleri and Scott Gomez also scoring for Montreal (15-14-2).

Jaroslav Halak was tremendous in net, finishing with 45 saves for his first road win of the season.

"He was the reason we won the game tonight, for sure," Cammalleri said. "He was solid from the start."

Canadiens forward Tomas Plekanec now has 12 assists in the last 10 games — along with two goals — after helping set up three goals at Scotiabank Place.

The Canadiens moved into a seventh-place tie with Ottawa in the Eastern Conference.

Montreal's first three goals were all a bit charmed. The Cammalleri goal ensued after a favourable bounce off one of the officials, the Bergeron slapper hit at least one and possibly two players, and the Kostitsyn insurance marker late in the third came seconds after Ottawa captain Daniel Alfredsson had hit the crossbar.

Gomez stripped Filip Kuba of the puck for an easy empty-net goal in the waning seconds.

The Canadiens got the figurative breaks, but may have suffered yet another literal one on their back end.

Jaroslav Spacek took a shot off the skate and had to be helped from the ice. He did not return. The Canadiens were already playing without Paul Mara, who left Monday's win over Philadelphia.

All-star Andrei Markov was injured in the opener and is out until at least January, while Hal Gill and Ryan O'Byrne have only returned in recent games.

The Senators went 0-for-7 with the man advantage, pushing Montreal's successful penalty-killing streak to 20 over the last five games.

"I thought that everybody that played on specialty teams did an outstanding job," Canadiens head coach Jacques Martin said.

While it's true Ottawa were too cute on a few of the power plays, they had a number of near-misses on others. Alfredsson sent a shot off Halak and trickling through the crease in the third, and he later redirected a shot into the post.

Mike Fisher scored his 13th for Ottawa (14-11-4), with Brian Elliott making 23 saves.

Montreal brings a three-game win streak into a home game against Pittsburgh on Thursday. Ottawa is in Philadelphia on the same night.

Halak gave an indication of what was to come by stopping Alex Kovalev and Nick Foligno in the same shift in the first. He then somehow blocked a Ryan Shannon offering with big Peter Regin impacting his view.

Halak in fine form for Canadiens

"They came out hard and they were shooting," Halak said. "That's when I got in the game."

Regin later in the frame drove to the net and picked up a loose puck, but couldn't lift his backhander high enough, shooting into Halak's glove.

At the other end, Elliott's best early save came on Sergei Kostitsyn's shot from the slot.

Cammalleri got his fifth in three games to put Montreal on the board at 18:32 of the first. Andrei Kostitsyn headmanned the puck, which went off an official and right to Plekanec midstride. The Czech forward set up a 2-on-1 goal, Cammalleri's third in as many games.

Fisher got Ottawa on even terms 1:46 into the second, roofing a backhander to finish a play started by Alfredsson and Milan Michalek.

The Canadiens began their string of penalties in the second, but nearly scored right after one lapsed. Travis Moen exited the penalty box and snuck behind the Ottawa defence, getting off a backhander on Elliott. The Senators goalie had no idea where the puck lay, with Tom Pyatt of the Canadiens sweeping the puck while falling down just wide of the net.

With Ottawa rookie Erik Karlsson in the box, Bergeron initiated a power-play goal for the second straight night with a slapshot. His shot definitely hit Jesse Winchester, and possibly nicked Andrei Kostitsyn as well.

The Senators outshot Montreal in every period, including 15-8 in the third, but Alfredsson couldn't buy a goal on his three close calls.

"We got a lot of pucks at the net but just didn't do a good enough job of getting pucks in the net," Senators centre Jason Spezza said.

Bergeron helped end all doubt after Alfredsson hit the bar, driving up the right side to fire a shot that left Elliott out of position. Kostitsyn potted the power-play rebound for a 3-1 lead with 2:12 to play.

Gomez, like Kostitsyn, scored his fourth of the season, but it took him two whacks to score into an empty net. The first hit the post.