Plekanec scored twice in regulation before setting up Souray in overtime during a 2-on-1. Souray, ejected from Montreal's 5-4 shootout loss in Pittsburgh on Wednesday for fighting with Colby Armstrong, one-timed Plekanec's pass and drove the puck past Marc-Andre Fleury into the right side of the net.
"He played a really excellent game and he's done that over the last few games," Souray said of Plekanec. "He's stepped up offensively and we need that. You look at his two goals, they were just the result of hard work and being in front of the net. He was willing to pay the price, and he got rewarded for it."
Sidney Crosby, who had an eight-game point streak broken Saturday in Pittsburgh's 2-0 win over Washington, assisted on power-play goals by Jordan Staal and Ryan Whitney. The 19-year-old forward leads the NHL with 59 assists and 84 points.
He also was stripped of the puck in the Canadiens zone by Plekanec on the play that led to the winning goal.
"I was just making a move, and when you make a move that high in the zone you know it could be trouble if you lose it there," Crosby said. "That's a bad area to lose the puck, so obviously I have to learn from that one."
The Penguins' streak was their longest since they won six in a row from Jan. 17-26, 2002. Pittsburgh has recorded points in 10 straight games (8-0-2).
Michel Ouellet tied it at 3 on the Penguins' third power-play goal, scored with 2:34 remaining in regulation. Ouellet deflected Ryan Malone's centering pass over David Aebischer's left pad for his 11th goal.
Plekanec tied the game twice, including his power-play tally 1:10 into the third which evened it at 2. Mark Streit converted Montreal's second power-play opportunity at 5:59 when he put a rebound of Michael Ryder's shot between Fleury's pads to give the Canadiens their first lead.
"I'm really happy that we turned around that game," Streit said. "It was such a big game for us."
Aebischer, making his third start in four games, stopped 31 shots. He is 2-0-1 over that stretch, including a 5-4 shootout loss in Pittsburgh on Thursday.
Crosby, a Nova Scotia native who grew up dreaming of playing for Montreal, set up Staal's 18th goal during a 5-on-3 midway through the first.
He added his second assist of the game on Whitney's 10th goal which restored Pittsburgh's lead 5:35 into the second.
The talented teenager was booed virtually every time he touched the puck, mostly because of his reaction to being struck by the butt end of Maxim Lapierre's stick during the game's opening faceoff.
Chants of "Faker! Faker!" rained down from the cheap seats amid the sellout crowd of 21,273 as Crosby slowly made his way back to the bench after he lingered on the ice while trying to draw a penalty in the third period.
"It's a road game," Crosby said. "I grew up liking this team and there's a reason they're passionate fans. That's how it goes. My like for the team's probably changed since then."
- The Penguins haven't won as many as seven straight since a 10-game winning streak from Jan. 28 to Feb. 15, 1999.
- Canadiens D Andrei Markov sat out because of an undisclosed lower body injury. D Janne Niinimaa replaced him in the lineup.