Last season, Montreal used a late 9-2-3 surge to claim the eighth seed in the Eastern Conference. This win lifted the Canadiens within one point of the struggling New York Islanders for the final playoff berth.
Zednik set up Mike Ribeiro just 7:09 into the game to give Montreal a 1-0 lead. Ribeiro scored from a tough angle on the right side, putting the puck off the goalpost and the left skate of goaltender Pasi Nurminen.
Zednik scored his 28th goal seven minutes later when he beat Nurminen with a one-timer from the low slot.
Dan Snyder got Atlanta on the board 69 seconds into the middle period with his ninth goal of the season and third in two games.
But Andreas Dackell scored a much-needed insurance goal late in the second. He trailed the play on the left side, drifted to the slot and got a pass from Niklas Sundstrom before one-timing a shot past Nurminen for his sixth goal.
Patrik Stefan lifted the Thrashers within 3-2 with 5:35 left in the third period, ending a nine-game drought.
But defenseman Andrei Markov found an empty net with 25 seconds remaining, nailing down Montreal's first three-game winning streak under coach Claude Julien. The last time the Canadiens won three in a row, Michel Therrien was behind the bench.