Lehtonen made 24 saves for his second shutout in three games and the Stars shut down Sidney Crosby and the Pittsburgh Penguins in a 3-0 victory in front of a sellout crowd at American Airlines Center.
"I've just been trying to do what I've been doing," Lehtonen said. "The guys in front of me played really well. In the first period, we were dominating. They got a couple of chances on the power play and that's it."
The Stars, who have outscored their opponents 14-1 during their winning streak, took the lead when Gonchar scored a power-play goal 15:02 into the game. The former Penguins defenseman fired a wrist shot from the high slot that rang off the far post before crossing the line for his second goal of the season.
Dallas got the power play when Olli Maatta was called for holding at 13:48. The Stars outshot Pittsburgh 10-4 in the first period.
"The last three games have all been excellent in all three zones," Stars coach Lindy Ruff said. "This one against a highly-skilled team and taking care of special teams probably knocks the other two down a little bit."
Benn gave Dallas a 2-0 lead when he roofed a shot over goaltender Marc-Andre Fleury at 3:13 of the second period for another power-play goal. Benn finished from the right circle following a pass from ex-Penguins defenseman Alex Goligoski, who picked up his eighth assist in seven games. The goal came with one second left in a roughing penalty against Kris Letang.
Dallas had two quick near-misses not long after Benn's goal. Tyler Seguin hit the left post with a wrist shot from the left circle at 5:19, and 16 seconds later, Ray Whitney drew iron when his wrist shot from the slot rang off the right post.
The Stars took a three-goal lead at 10:20 when Peverley sent a wrist shot from the right circle over Fleury's glove for his seventh of the season. Shawn Horcoff stole the puck from Evgeni Malkin in the neutral ice and fed Peverley, who raced up the right side.
Penguins coach Dan Bylsma said the loss boiled down to his club being unable to match Dallas' effort.
"They're really pushing hard right now to get into the playoffs. This is desperation for them and we saw that in their last two games. We saw it again tonight," Bylsma said. "This was a desperate team, played hard. We have to be able to match that regardless of where our position is or what the standings look like."
Dallas drew iron twice more early in the third period; Benn hit the crossbar at 1:32 and Cody Eakin did the same with a rebound at 3:54.
Malkin generated one of Pittsburgh's better chances 90 seconds later. With the Penguins on a power play, he blistered a slap shot from the right circle that Lehtonen was able to deflect with his glove.
"He was rock solid," Ruff said of Lehtonen. "With the team in front of him for the first 40 minutes, you couldn't find more than one or two good chances. In the third period when he really needed them, he stood tall. He's really been big for us. There haven't been any bad goals."
Pittsburgh's power play, which heading into the game was the NHL's fourth best on the road and No. 1 overall, finished 0-for-4.
"We knew they were going to come out hard," said Crosby, the NHL's leading scorer. "They did exactly what we expected. They capitalized on their power plays. We didn't. We didn't execute when we got chances."
Dallas was 2-for-3 on the power play and has at least one power-play goal in seven consecutive games.
"We knew we would have to show discipline and score on the power play to win," Ruff said. "On the penalty kill, we got sticks and got bodies in the way. They didn't get real good chances."
The Stars' power play has scored at least once in each of the last seven games and is 9-for-24 (37.5 percent) during that stretch.
"That was quite a task," Eakin said. "[Crosby] is obviously one of the best. I was 1-on-1 with him behind the goal, where he is the best. That was pretty tough. I tried to muscle him there. We were sharp, quick and crispy and it worked out for us."
Pittsburgh (36-14-2) ended a stretch of four games in six days that started with a 5-1 loss to the Florida Panthers on Monday, followed by wins against the Montreal Canadiens and New York Islanders.
"I think it's work ethic right now," forward Craig Adams said of his team's erratic week. "I think it's shortcuts and thinking it's going to come easy. It's a good League. It's good teams and you can't take any shortcuts."