Lehtonen entered the record books upon being selected by the Atlanta Thrashers with the No. 2 pick in the 2002 NHL Draft. It represented the highest NHL Draft position ever for a European goaltender or Finland-born player.
He also made a bit of history with Atlanta. Lehtonen was the No. 1 goalie on the only Thrashers team to make the Stanley Cup Playoffs, in 2006-07 (they became the Winnipeg Jets for 2011-12). He went 34-24-9 with a 2.79 goals-against average and a .912 save percentage for Atlanta that season.