For the second straight series, the eighth-seeded Canadiens forced a seventh game and then eliminated a team that played for last year's Eastern Conference title.
Montreal came back from a 3-1 deficit in the opening round to knock out top-seeded Washington and the Canadiens rallied from a 3-2 hole to oust the defending Stanley Cup champion Penguins. The Game 7 win over Pittsburgh came in the last hockey game scheduled to be played in Mellon Arena.
Pittsburgh attempted to set a physical tone early, only to have that strategy backfire when Sidney Crosby was called for a boarding penalty just 10 seconds into the game.
Gionta promptly capitalized, scoring on the power play with a mere 37 second having expired.
That goal stunned the home crowd and the home goaltender as well. Marc Andre-Fleury went on to allow four goals on nine shots through the first five minutes of the second period and gave way to Brent Johnson.
Dominic Moore made it 2-0 with 5:37 left in the first period, Mike Cammalleri scored his league-leading 12th playoff goal 3:32 in the second and Travis Moen produced a shorthanded score less than 2 minutes later.
Chris Kunitz and Jordan Staal then produced Pittsburgh goals before the second period was over, giving the Penguins hope for a comeback. But Gionta tipped in a shot from Cammalleri midway through the third and Jaroslav Halak turned in a perfect period while making 37 saves overall.
Mellon Arena, known throughout the NHL as "The Igloo," was opened in 1961 and is the oldest arena in the league. Pittsburgh will open the 2010-11 season in the Consol Energy Arena.