Martin Kariya had a goal and an assist for the Blues (1-2). Marian Hossa scored both goals for the Thrashers (2-2).
King intercepted a pass by rookie defenseman Nathan Oystrick just outside the blue line and skated in all alone against Atlanta goalie Johan Hedberg for the tiebreaking goal.
Hossa gave the Thrashers a lead 3:59 into the first period, knocking a rebound past starting goalie Juuso Riksman. The Blues had a rebound goal of their own 3:59 into the second period, with Kariya scoring.
Hossa scored a short-handed goal at 12:53 of the second period, backhanding the puck over substitute goalie Hannu Toivonen. But the Blues tied it on David Perron's goal off a feed from Kariya at 18:31 of the period.
The Blues outshot the Thrashers 26-21. Riksman had 10 saves and Toivonen nine for St. Louis, including a big stop in the closing seconds.
Kari Lehtonen was scheduled to make his preseason debut in goal for the Thrashers, but is bothered by a tender groin. Hedberg made 23 saves.