Lehtonen, who passed Miikka Kiprusoff for the most NHL games played by a Finland-born goaltender (624), made 15 saves in the first period. Lehtonen, 34, is 300-223-65 in 14 NHL seasons.
"It's a huge moment for him, but man, he was good tonight," Stars coach Ken Hitchcock said. "He had to earn it. He had to work. He had the help of the [goal posts] three times. He had to earn it tonight. This is one you've got to look and say the goalie was your best player, because to win in this building and against that team, your goalie is going to have to be your best player."
The Stars made it 3-0 at 1:01 of the second period when Elie scored on a rebound during a delayed penalty. Halak was pulled after Benn made it 4-0 with a wrist shot from the slot at 9:21.
Pitlick scored his second when he redirected John Klingberg's wrist shot 21 seconds into the third period to make it 5-0.