Slava Kozlov and Sim, the fourth Atlanta shooter, beat Chris Mason in the shootout, while only Paul Kariya was able to score against Fred Brathwaite. Jean-Pierre Dumont had a chance to tie it for Nashville after Sim's goal, but missed.
Dan Hamhuis scored twice for Nashville. Hamhuis played all 82 games for Nashville last season but became a restricted free agent and did not re-sign until last week.
Scott Mellanby and Steve McCarthy scored for Atlanta (2-3-1) in the second period to give the Thrashers a 2-0 lead. Hamhuis put Nashville (3-1-1) on the board with a backhander at the 19:41 mark of the period.
Kariya tied it on a short shot at 11:04 of the third, and Hamhuis scored the go-ahead goal on a long slap shot with 1:38 left in the period.
Nashville's Greg Zanon was called for holding with just over a minute to play. The Thrashers pulled Brathwaite, and Sim tipped in Mellanby's shot in the final seconds.
Goalie Kari Lehtonen played the first two periods for the Thrashers and stopped 11 of 12 shots. Mason played the entire game for Nashville and made 16 saves on 19 shots before the shootout.
Brathwaite played the third period for Atlanta and made six saves in eight chances.