The Lightning failed to capitalize on a two-man advantage in the extra session, but center Vincent Lecavalier picked up a loose puck moments later and moved in unopposed on goalie Ondrej Pavelec and set up a backhander by St. Louis.
Tampa Bay starting goaltender Mike Smith allowed one goal in two periods to earn a long-awaited win. Smith was barely tested in his first period since the lingering effects of a concussion sidelined him with 10 weeks remaining last season. He needed only four saves to protect a 1-0 lead provided by Ryan Malone, whose power-play goal beat Pavelec on the glove side with 3:08 left in the period.
It took just 3 seconds, however, before the only crowd Tampa Bay will host before the regular season was cheering. Immediately after the faceoff, Zenon Konopka of the Lightning and Atlanta's Josh Gratton began trading punches. They fought again with 6:31 to go in the third period, this time with Gratton being charged with a game misconduct.
The Thrashers, who lost 5-0 in their preseason opener Thursday at Nashville, finally broke through on a tip-in by Paul Postma at 9:10 of the second.
Smith made 18 saves and withstood three Atlanta power plays before giving way to rookie Dustin Tokarski, who stopped all seven shots he faced in the third period and two in overtime.
Pavelec finished with 32 saves and foiled Tampa Bay on seven of eight power-play attempts while going the distance in his preseason debut.