In the second round, Benn cut out to the right before coming back to the middle and snapping a wrister into the left side of the net past Niklas Backstrom.
Mike Ribeiro scored the lone goal for the Stars, who have won three of four. Lehtonen made 33 saves in the win.
"Our penalty killing was very good. That helped also," Lehtonen said. "It was fun for me getting a lot of shots and then the two points at the end."
Kyle Brodziak scored the only goal of the game for the Wild, who have lost six of nine. Backstrom turned away 25 shots in the loss.
"We had a lot of luck, some good chances," Brodziak said. "If we keep playing like that we're going to have some success."
After a scoreless first period, Dallas took a 1-0 lead with 4:48 to play in the second on the power play. A blast from the high slot by Alex Goligoski went high, but it took a bounce off the backboards and went to the right. There, Ribeiro grabbed the puck and skated to the slot before snapping it in.
The Wild, though, tied the game 5:18 into the third as a turnover in the Dallas end saw Brodziak wind up with the puck and skated to the low right side to get Lehtonen out of position for his 15th of the season.
Minnesota plays at Columbus on Tuesday...Dallas hosts the Coyotes on Tuesday...Minnesota took a 5-2 decision over Dallas in Minnesota on January 21...Dallas went 1-for-2 on the power play while Minnesota was 0-for-4.