MONTREAL – The Eastern Conference semifinal series between the Canadiens and the Pittsburgh Penguins has been reduced to a one-game, winner-take-all affair.

The Canadiens parlayed two goals by Michael Cammalleri, a timely return by defenceman Jaroslav Spacek, an unlikely game-winner from Maxim Lapierre and another solid performance by goaltender Jaroslav Halak to beat the Penguins 4-3 Monday night.

That knots the best-of-seven series at three games apiece with Game 7 scheduled for Wednesday night at the Mellon Arena in Pittsburgh (7 p.m., CBC, RDS, CJAD Radio-800).

Lapierre gave the Canadiens a 4-2 lead with a great individual effort at 11:03 of the third period. He picked up a puck in the neutral zone, used his speed to beat Alex Goligoski down the left side and then cut in front of the net to beat Marc-André Fleury.

That goal proved to be crucial because Bill Guerin deflected a shot by Sergei Gonchar to bring the Penguins to within a goal at 18:36. Halak made 34 saves as the Canadiens staved off elimination for the fourth time in this year’s playoffs.

The Canadiens were being outplayed by a wide margin when they scored two goals in a span of two minutes and 31 second to grab a 3-2 lead in the second period.

Cammalleri scored his second of the night when he took a pass from Andrei Kostitsyn and beat Fleury at 10:45 to tie the score at 2-2. Cammalleri is the leading goal-scorer in the playoffs with 11.

Jaroslav Spacek gave the Canadiens a 3-2 lead when he scored on a shot from the blueline at 13:15. Spacek, who had missed nine games with an undisclosed ailment, was a last-minute addition to the lineup after coach Jacques Martin decided that Hal Gill wasn’t ready to play. Gill, who was cut on the back of his left leg in Game 5, participated in the morning skate and the pregame warmup before being scratched.

Penalties were the Canadiens’ undoing earlier in the second period. Montreal killed off a holding penalty to Lapierre as Halak made three saves and had the hockey gods on his side when Sergei Gonchar and Evgeni Malkin hit goalposts.

But Roman Hamrlik was called for interference 20 seconds after Lapierre returned to the ice and Montreal native Kris Letang scored at 5:21 to snap a 1-1 tie.

Cammalleri opened the scoring when he combined with Tomas Plekanec on a rush at 1:13 of the first period. Cammalleri passed to Plekanec in the middle and then took a return pass on the right wing and beat Fleury with a one-timer high on his glove side.

The Penguins tied the score at 7:22 when Mark Eaton’s shot from the point was blocked in front, but Sidney Crosby batted the loose puck out of the air. It was Crosby’s sixth goal of the playoffs but his first in this series.