The Thrashers had lost four of five to the Lightning this season, including an 8-0 blowout in their previous meeting on Dec.7.
Slater's second goal of the season was reviewed for several minutes by officials because of a potential high stick. Slater's shot beat goalie Johan Holmqvist, who appeared to be screened. Niclas Havelid and Shane Hnidy got assists on the goal, which ended the Lightning's three-game winning streak.
Martin St. Louis scored Tampa Bay's only goal in the first period. Atlanta tied it in the second on a goal by Vyacheslav Kozlov.
The Lightning took a 1-0 lead on a short-handed goal by St. Louis, his 24th. He beat goalie Kari Lehtonen from in close at 15:34, and Vincent Lecavalier got an assist. Tampa Bay has five short-handed goals, three by St. Louis.
The Thrashers tied it in the second on a 30-foot shot by Kozlov, his 14th goal. Marian Hossa and Jason Krog assisted.
Notes: Tampa Bay didn't have a shot on goal in the first period until 12 minutes had gone by, but wound up with seven in the period, the same as Atlanta. ... The Thrashers had a two-man advantage for 52 seconds early in the first period, but failed to capitalize. ... Lecavalier had three goals and three assists in his previous three games. ... Kozlov played in his team-record 137th consecutive game. ... St. Louis had a goal and four assists in the 8-0 win over Atlanta.