Lehtonen's teammates made sure their goaltender was rewarded for his efforts by playing a strong third, and the Stars left Rogers Arena with their third straight win on a swing through Western Canada.
Erik Cole snapped a scoring slump with a goal early in the third, helping the Stars to the 2-1 win.
Lehtonen was the difference Sunday night, making 20 of his 42 saves in the second period.
"Kari was great for us tonight," Cole said. "You could tell he had great focus and was on his game, and (he) really weathered the storm in the second period. He's been fantastic. Night after night, he continues to surprise even us by making unbelievable saves."
Lehtonen had a couple of those against the Canucks, denying Henrik Sedin on a breakaway 25 seconds into the game, sliding across to rob Kevin Bieksa on a one-timer in the second period, and adding a couple late saves in the game's closing minutes.
But the Dallas goaltender also got a break when Henrik Sedin had what would have been a game-tying power-play goal waved off for incidental contact with the goalie.
Sedin's sharp-angle goal was called off when the officials ruled twin brother Daniel Sedin bumped Lehtonen atop the crease. Replays didn't show much, if any, contact with Lehtonen, who appeared to stumble trying to get back as the puck deflected from his left to right, where it found a wide-open Henrik Sedin.
"It's a bad call," said Henrik Sedin, who made the scoresheet on the man advantage three minutes into the third, spoiling Lehtonen's bid for a second shutout in three games. "It's a made-up call. If it's a 50-50 call, then I buy it. If it's a 40-60, I buy it. Even 20-80. … Tough to take."
Even Lehtonen was surprised to get the call.
"It's one of those things I thought they would not call it, but when you see it, maybe there is something but not too much," Lehtonen said. "It happens so fast and I've said it before, I wish they would maybe use some video replay or something just to make them right."
Canucks coach John Tortorella made a similar plea.
"It's a big play in the game. I think we need to get the call right," Tortorella said. "All the crap we review, and they don't review an important thing like that. I just think that needs to change. It's the wrong call."
It was not, however, the reason Vancouver lost its fourth straight.
The Canucks have scored one goal in each of the four losses despite carrying the play for long stretches in each and averaging 35 shots.
"We're professionals," said Ryan Kesler. "We've got to start burying those chances. Really, enough is enough. We have to bear down and not get frustrated, but we have to capitalize. That's on us."
After getting outshot 20-6 in the second period, Dallas (11-7-2) tightened up in its own end in the third, holding Vancouver to 10 shots.
"Big 20 minutes by them, and Kari stood tall for us through it," coach Lindy Ruff said, crediting his team for bouncing back from that second period. "Go watch the third period again. Defensively, we eliminated the grade-A chances and had as many as them."
Cole buried the Stars' best chance, doubling the lead on a 2-on-1 rush 1:42 into the third. Cole one timed a perfect cross-ice pass from Cody Eakin past the glove of a sprawling Roberto Luongo for his first point in nine games and first goal since the second game of the season.
"(Eakin) showed great patience on the pass to let the guy slide through the lane and was able to get it over to me," Cole said. "Pretty nice to start contributing a little more."
Rookie Valeri Nichushkin opened the scoring for the Stars, who have won six straight road games.
After combining for 13 points in a 7-3 win against the Calgary Flames on Thursday, the Stars' top line didn't take long to open the scoring in Vancouver. Tyler Seguin, who had four goals and an assist in Calgary, won a battle with defenseman Alexander Edler behind the Canucks net and fed it out front to Nichushkin cutting hard to the net for a one-touch shot through Luongo before the goalie could seal the short side.
It was the second goal of the season for Nichushkin, an 18-year-old rookie who had two assists against the Flames. The assist extended Seguin's point streak to four games (six goals, two assists).
"We're building confidence as a group," said captain Jamie Benn, who had six points in Calgary and the second assist on Nichushkin's goal against the Canucks on Sunday. "Starting from our last road trip going into some tough buildings in Boston and Detroit, and just continuing on this trip, we're finding ways to win.
"Some are prettier than others, but we're getting the job done."
Lehtonen, who now has a .934 save percentage, has been a big part of it. He credited a breakaway save on Henrik Sedin in the opening minute for setting the tone against the Canucks.
Dallas opened the scoring five minutes later.
"It started kind of the way you don't want to, with one of the Sedins on a breakaway, and when I was able to stop that, it makes me a lot more comfortable, and it just went from there," he said. "I got lots of shots, and a couple good bounces and a post and one no-goal there too."
Luongo finished with 21 saves for the Canucks (11-8-3).
Vancouver played with its top nine forwards for the first time this season with the return of Jannik Hansen, who missed 10 games with a shoulder injury. Vancouver shook up its lines to try to muster some offense, dropping Kesler from wing on the top unit to center the second line, and trying to spread out the attack.
Despite 43 shots, it wasn't enough against Lehtonen.
"When you are able to make the saves, you want 60 shots, but this was plenty," Lehtonen said. "They were coming hard."