MONTREAL -- The Montreal Canadiens were short yet another key defenseman for Game 6 of this Eastern Conference Semifinal series when Hal Gill was unable to play.

Fortunately for them, one of the other members of their walking wounded defense corps was able to return, and Jaroslav Spacek proved to be a big boost in a 4-3 victory that forced a seventh game. Not only did play more than 18 minutes in his first action in 20 days, Spacek scored the go-ahead goal in the second period.

"He's missed three weeks and he came back and was a big factor in our win tonight," Montreal coach Jacques Martin said. "He gave us some important minutes and I thought he got stronger as the game wore on."

Added forward Tom Pyatt: "The way he played, he looks like he didn't miss any games. He came in there and looks like he's been in every game this playoffs. Those are the kind of players we need stepping up and he was just tremendous."

Spacek played the first three games of the first-round series against the Washington Capitals, but had been missing ever since because of an undisclosed injury described only as an illness. He has been skating with the team for several days, but Martin continued to say he wasn't ready.

Not having Gill, as well as blueliners Andrei Markov and Paul Mara, proved to be the opening Spacek needed to give it a try.

"Last night I felt I would be going and I would have a good game. I wanted to play," Spacek said. "You never know with the injury that I had, it's tough to wake up in the morning and not know what happened. But I felt good and I told the guy I'm ready to go, especially when Hal went down, I think to help out."

Spacek's goal came two-and-a-half minutes after Michael Cammalleri had tied the game at two in the second period. The momentum had started to swing in Montreal's favor, and Spacek helped his team capitalize.

Brian Gionta ripped a slap shot from the top of the offensive zone, but the puck didn't make it through. It went near the left wall to Scott Gomez, who corralled it and waited patiently for the play to develop. Gionta went to the net to add more congestion, and Gomez sent the puck back to the top where Spacek was waiting.

All of the Pittsburgh defenders had collapsed in near the front of the net and goaltender Marc-Andre Fleury had trouble seeing Spacek's shot through the bodies. It was a low blast and beat Fleury before he realized where it was.

"It was nice to score. I didn't score for probably 50 games," said Spacek, who last scored Dec. 4 against Boston. "That's a long time. It was kind of tough for me to play in the first period, but after that it was kind of a relief. It was a good, solid team effort."

Spacek also had a strong game defensively. He made two diving plays to break up chances for the Penguins, including one when Sidney Crosby tried to saucer a diagonal pass to Bill Guerin on a rush, but Spacek was able to get the end of his extended stick on the puck to knock it away.

"I was more on my knees than I was on my feet," Spacek said. "I felt pretty good later on. It was better and better. I was a little bit scared to go out there. You start to feel better and better, and when you get a comfortable lead I don't want to say it is easier to play, but we had good habits. I didn't play for three weeks, and to jump in like this in Game 6, you want to go out there and give your best."