OTTAWA, Ontario -- Carey Price called it one of his best performances of the season.
"The reason for tonight's win is Carey Price," Canadiens coach Michel Therrien said. "He kept us in the game through two periods. I thought he was extraordinary."
Price made a number of big saves and at one point had many of the Senators wondering if they would find a way to beat him.
"He was the difference in the game," Senators forward Bobby Ryan said. "When he saved me I thought this is going to get ugly here and then he made the 10-beller on (Mark) Stone right afterward. I just got lucky enough to get another opportunity right away."
Through two periods, Price had faced 38 shots and admitted he felt good despite having to be so busy.
"It was fine," Price said. "That's what we train for all year."
The Canadiens got off to a great start by jumping out to a 3-0 lead, but four unanswered goals allowed the Senators to start the third leading 4-3.
After giving up the lead in the second, Price said little needed to be said.
"There was a few things said, but we've all heard those speeches before," Price said. "We knew what needed to be done. Our leaders took over and did a good job."
The Canadiens caught a break on the tying goal midway through the third. Tomas Plekanec broke in alone and while Craig Anderson made the initial save, defenseman Jared Cowen watched as the puck went in off his skate.
"I couldn't even get out of the way because I was stopping," Cowen said. "Just one of those things where you feel like you're helpless. In the end it's just one of those terrible feelings you feel in the pit of your stomach."
The game then went to overtime where Subban scored 23 seconds into the extra period as his shot trickled through Anderson's legs.
Despite the loss, the Senators felt they played well and showed a lot of resiliency.
"I thought we did a lot of good things," Ryan said. "I thought we controlled the pace most of the game. It's a loss and it's a negative in that regard, but I think everyone in the room can take a lot of positives from it."
Two goals in 84 seconds late in the second allowed Ottawa to grab its first lead of the game.
A great pass by MacArthur allowed Turris to beat Price over the shoulder, giving the Senators a 4-3 lead.
Trailing 3-2 to start the second, Ottawa outshot the Canadiens 19-10 in the second and tied the game on the 37th shot as Ryan beat Price with a wrist shot.
Minutes earlier Price had made outstanding saves on Ryan and Mark Stone.
"(Price) had a great second period," MacArthur said. "He did a great job so you have to give him credit, but on our side we have to find a way to win those games."
The Canadiens got off to a quick start taking a 3-0 lead early in the first, but with two late first-period goals the Senators rallied.
Plekanec opened the scoring with a short-handed goal on Montreal's first shot at 2:04. Pacioretty made it 2-0 with a power-play goal at 14:05 as he roofed it over Anderson's shoulder.
And at 15:36, Desharnais made it 3-0 as he was allowed to walk in alone and drew Anderson out to have a wide open net.
Ottawa's comeback started at 17:13 as Karlsson found MacArthur in the middle who then tipped a shot through Price's legs.
Just over a minute later, Karlsson scored his 11th of the season off a pass from Jason Spezza to draw the Senators within one.
D Patrick Wiercioch and D Joe Corvo were healthy scratches for the Senators. RW Chris Neil was a late scratch, he has missed the past six games with a lower body injury. Matt Kassian took his place in the lineup. D Francis Bouillon was a healthy scratch for the Canadiens. Montreal is playing the first of a four-game road trip.