Shortly into the 2006–07 season, Lehtonen broke the Atlanta Thrashers shutout streak record previously held by Michael Garnett. He also set his career highs in every category. AirTran Airways, a low-cost airline, signed Lehtonen as an endorser for the 2006–07 season. On February 8, 2007, Lehtonen became the Thrashers franchise leader for wins by a goaltender with 49, surpassing Pasi Nurminen's record of 48. On April 12, 2007, Lehtonen was the starting goaltender for the Thrashers in their first Stanley Cup playoff game.