After Johan Hedberg had 29 saves in regulation and overtime for the Thrashers, he was pulled for Kari Lehtonen. The Flyers jumped all over the goalie change, with Gagne and Forsberg scoring on the Flyers' first two shots.
Vyacheslav Kozlov, who scored in regulation, had the only shootout goal for Atlanta on its first shot. No one else could slip one past steady Antero Niittymaki, who had 27 saves.
This was the boost the Flyers desperately needed five days after Stevens was promoted from first-year assistant to coach, hoping to nudge them out of last place.
The Flyers entered with the worst record and fewest points in the NHL, a shaky start that resulted in one of the most drastic shakeups in team history. Longtime general manager Bob Clarke resigned and coach Ken Hitchcock was fired Sunday with the Flyers on their first five-game losing streak since 2002 and off to their worst start in 17 years.
Forsberg, Gagne and Niittymaki ensured the losing streak wouldn't stretch to six. And while 2-6-1 hardly sounds promising, the win was a strong start to a five-game homestand.
Still bothered by a sprained left wrist that kept him out of one game, Forsberg delivered when needed in an already-big early-season game. Not only that, he scored on a power play.
The Flyers were a measly 4-for-55 on the power play this season, 0-for-15 the last three games, and squandered their only other opportunity against Atlanta. With Andy Sutton still in the box from a second period holding penalty, Forsberg knocked the puck off Hedberg's pads from close range only 56 seconds into the third for a 2-1 lead.
Forsberg raised his stick in celebration and finally got a rise of a surprisingly smaller crowd than the traditionally packed arena the Flyers are used to.
Vyacheslav Kozlov, though, tied it 2-all midway through the period with slapshot that stunned Niittymaki.
Playing at home may have been a spark for the Flyers. The Flyers played six of their first eight games on the road, including a 9-1 loss at Buffalo that convinced chairman Ed Snider he needed to fire Hitchcock after three-plus seasons without a Stanley Cup finals appearance.
Though Stevens said he expected some pregame jitters, he appeared relaxed behind the bench, his hands behind his back, watching many of the same players he coached to a minor-league title two seasons ago.
The Flyers got an early lift about 2 minutes into the game when Mike Knuble snagged the loose puck down the right side just past the blue line and made a nice feed to Randy Robitaille who scored for a 1-0 lead.
Atlanta came back about 5 minutes later when Kovalchuk was left all alone and streaked down centre ice for an easy breakaway goal, tying the score at 1.
Notes: Kovalchuk has scored a point in six straight games. ... The Thrashers finished their second set of back-to-backs this season and play the fourth game of a five-game, eight-day road trip Saturday at Buffalo.