OTTAWA -- Usually when a defensemen is taking part in a shootout, a number of forwards have already been used.

But Guy Boucher only waited until the fourth round before taping Erik Karlsson on the shoulder Saturday night at Canadian Tire Centre.

"I've done some worse things," the Senators coach said with a grin after Karlsson's goal gave Ottawa a 4-3 victory over the Montreal Canadiens. "I've had stars that weren't scoring, so I put my fourth liners and third pair defensemen and we were winning in shootouts.

"Sometimes you just smell things and you follow your gut feeling. Sometimes it works, sometimes it doesn't. Sometimes you look like a genius, sometimes you look like an idiot.

"This time I look like a genius."

The victory was the second in extended time for the Senators, who improved their record to 2-0-0 under Boucher. The Canadiens slipped to 1-0-1.

With a goal and three assists, Karlsson is leading the Senators in scoring, just as he has the past three seasons. But rare is it that he finds himself in alone on a goalie, and he estimated he only takes part in the shootout "one or two" times a year.

"I had my move before I even went in," said Karlsson, who moved the puck from his backhand to his forehand before beating Canadiens goalie Al Montoya with a low shot to the stick side that went in off the post. "I was sticking to it no matter what, since I don't have that much in my arsenal any more."

Senators winger Tom Pyatt, who started his NHL career with the Canadiens, scored his first goal for Ottawa with 2:33 left in the third period to send the game into overtime. Wingers Ryan Dzingel and Zack Smith had the other Ottawa goals, while defensemen Chris Wideman chipped in with a pair of assists,

Defenseman Jeff Petry scored twice for the Canadiens while rookie winger Artturi Lehkonen added his first in the NHL.

Montoya, who is filling in for flu-bitten Canadiens goalie Carey Price, made 35 saves. Senators goalie Craig Anderson stopped 21 shots.

The Canadiens entered the third period trailing 2-1 but Lehkonen and Petry had them in front with 11 minutes to go. Petry, who was playing his first game after missing the opener in Buffalo with a knee injury, blamed himself on Pyatt's equalizer, a pretty three-way passing play that included center Jean-Gabriel Pageau and Dzingel.

"I read late our forward going after the middle guy," Petry said. "I took a step towards the middle guy and then tried to fade off to the guy on the outside. If I had seen him earlier, I would have just gone right to the guy at the backdoor."

The Senators bolted from the gate, killing off two penalties in a first period that saw them jump into a 2-0 lead while outshooting the Canadiens 13-6.

"We had a really slow start," Canadiens coach Michel Therrien said. "For the first half of the game we weren't skating the way we're capable of skating. You've got to give the Sens a lot of credit, they played good. We made some adjustments and that was positive for us and halfway through the game I thought we started to skate, put more pressure and attack the net a lot more than we did in the first half."

Canadiens center David Desharnais had a chance to answer Karlsson's goal in the shootout, but he lost the puck and didn't get a shot off.

"You just try to be patient and out-wait him," said Anderson. "He's got his head up to see what he might have available, and he just kind of lost the puck there.

"We'll take it any way we can. Bobby (Ryan) misses the net and they get a freebie save on that one, so we'll take the freebie on the other end, too."

Boucher was pleased that the Senators held such a wide margin in the shots on goal department. The Senators only outshot their opponents 21 times last season.

"The goal of this team, first and foremost, is to give up less shots," he said. "You play against such a good team that's supposed to be Top 2, with Tampa ... we knew we were up against a really good team, and our guys came out charging.

"These are good games, we need to have those games, especially at the beginning," he added, referring to starting the season with a pair that extended beyond the third period. "They build your character and your resiliency."

The Canadiens, meanwhile, we're unhappy with their finish.

"With a couple of minutes left, we've got to shut it down," said winger Alexander Radulov.

NOTES: Senators D Thomas Chabot and LW Matt Puempel were healthy scratches for the second straight game. With back-to-back contests coming up Monday and Tuesday, Ottawa coach Guy Boucher said both Chabot and Puempel will make their respective season debuts this week. ... Canadiens D Mikhail Sergachev was scratched after playing in the season opener. ... Montreal D Zach Redmond was a healthy scratch. ... Canadiens C Bryan Flynn missed the game with a neck injury. ... Canadiens D Jeff Petry returned after missing the first game with a knee injury.