BOSTON - Alex Kovalev turned his season around just in time to spark the Montreal Canadiens to an unprecedented upset.

For the first time in their rich history, the Canadiens won a playoff series in which they trailed 3-1. And for the second time in three years, they knocked off the favored Boston Bruins in the first round.

"Our players showed a lot of character," Montreal coach Claude Julien said. "It would have been easy to throw in the towel after we lost that fourth game."

The former Penguin assisted on Richard Zednik's two third-period goals in the Canadiens' 2-0 win Monday that clinched the series in seven games. But in Game 4, Kovalev was the prime culprit in an overtime loss.

He was hit on the arm near Montreal's blue line and held it while allowing Glen Murray to go by him for the winning goal. It was just one more bump in a season in which he had only one goal and two assists after Montreal obtained him from the New York Rangers.

"The most important thing was to save it for the playoffs," Kovalev said with a smile. His next series will be against Tampa Bay, which had the best record in the Eastern Conference.

Julien gave him time to regain his productivity.

"He had a tough year, so we had to give him time to turn the corner," Julien said. "We tried not to put too much pressure on him."

There was plenty of self-imposed pressure on Bruins captain Joe Thornton to play in the series after he missed the last two regular-season games with what coach Mike Sullivan called "an upper body injury." Once the series ended, Sullivan said it was a painful rib injury.

"Most players in the league wouldn't have played," Sullivan said.

Thornton, Boston's top scorer, didn't get a point even though he played in all seven games against the Canadiens.

The Bruins had just three goals in the last three games against Jose Theodore, who posted the first playoff shutout of his career even though Boston played well for most of the night.

The Canadiens were 0-12 in seven-game series they trailed 3-1. They got as close as 3-3 just one other time, in 1954. The Bruins were 17-0 when ahead 3-1.

At Vancouver, British Columbia, Martin Gelinas scored a power-play goal 1:25 into overtime and Calgary won a playoff series for the first time since 1989.Jarome Iginla scored twice and Miikka Kiprusoff stopped 26 shots as the Flames captured a series for the first time since winning the Stanley Cup 15 years ago. The sixth-seeded Flames will face No. 1 Detroit in the Western Conference semifinals.