Lehtonen made 21 saves for the Stars (13-13-5), and Jamie Benn had a goal and an assist in a 2-1 win against the Flames at Scotiabank Saddledome.
"After the shutout it was an easy decision to come back with Lehtonen," Ruff said. "To go the other way, I could've got heavily criticized."
Ruff had originally planned to start Anders Lindback in one of the first two games of Dallas' three-game Western Canada road trip, which concludes Sunday against the Edmonton Oilers. Instead, he again went with Lehtonen, who has won three straight starts and allowed eight total goals in winning four of his past five.
"It's been a long time coming," Lehtonen said. "It's been such an up-and-down season so far. It's been nice to be able to play a few good games in a row now. That gives confidence to everybody, and I think that's a sign too that our guys are starting to play really well in front of me.
"When things go well you want to play and play and play. We'll see what's going to happen in two days and we'll go from there."
It was the seventh straight regulation loss for the Flames (17-15-2), who had not lost seven in a row since the 1974-75 season. It's the first time Calgary has gone seven consecutive games without a point since Dec. 22, 1998, through Jan. 5, 1999.
The Flames, who have not won since a 4-3 overtime victory Dec. 4 against the Colorado Avalanche, have 11 goals in the seven losses.
"It's tough," Flames captain Mark Giordano said. "It's more than a rut now. It's seven games now that we haven't got a point. The thing about our start (to the season) was that we didn't fall out of it. We're still right there. We have to find a way now to get one. First, we get one, and then try to string some together. We have to start trying to generate more goals, obviously.
"We're digging, we're going to the net, we're trying, but I think whether it be from an individual standpoint or a team standpoint, we have to make a better effort at banging some ugly ones in. That's how we're going to get out of this. And when we do get chances, if you get a good look, you have to put it on yourself and try to bury it."
Benn put the Stars ahead 1-0 at 4:00 of the second period, lifting the stick of Flames defenseman Kris Russell in front of the Calgary net before sliding a backhand by the outstretched pad of goaltender Jonas Hiller.
"I just kind of pick-pocketed him there," Benn said. "It was kind of a lucky break. I think [Cody Eakin] lost the draw and it came right to me."
With three Flames forwards caught deep on an expiring penalty to Dallas defenseman John Klingberg, Eakin moved the puck ahead to Benn, who gained the Calgary zone before spotting Daley. The Dallas defenseman corralled the pass and snapped his seventh goal short side by a sprawling Hiller at 11:54 of the second.
"We found a way to get a rush chance and took advantage of it," Benn said. "Daley made a great shot there. We'll take that when we can."
The Flames cut the deficit to one before the second intermission.
Lehtonen couldn't handle the Flames' initial dump-in cleanly and shuttled the puck to the corner. Calgary retrieved it and Paul Byron eventually worked it back to Mark Giordano, whose wrist shot from the point fluttered underneath Lehtonen with 1:15 remaining in the period.
Lehtonen ensured that total didn't increase.
He stopped defenseman Raphael Diaz's initial shot from the point as well as center Markus Granlund's rebound attempt three minutes into the period. He made another big save on Hudler's tip attempt a little more than four minutes later.
With Hiller pulled in favor of the extra attacker, Flames defenseman TJ Brodie hit the post with 1:22 remaining. After Dallas forward Tyler Seguin was called for tripping with 27.2 seconds remaining in the third period, Calgary had a 6-on-4 advantage but couldn't find the tying goal.
Despite chances to open the scoring, the Flames couldn't find a break in the first.
David Jones beat Lehtonen with a shot 3:36 into the game, but it hit the post. Halfway through the opening period, Curtis Glencross jumped onto the ice and into the Stars zone, taking a pass from Dennis Wideman down low, but Lehtonen made a glove save to keep it scoreless. With 4:10 remaining in the period, Gaudreau fed Josh Jooris a one-timer that made its way through Lehtonen, but the puck slowed up enough in the crease in time for Dallas to clear.
"We did get some good looks and we didn't bury them," Giordano said. "That's the bottom line. When you don't score more than one goal in as many games as we have now on this streak, we have to look in the mirror and say, 'Hey, we have to maybe change it up a bit offensively and try to grind some goals in."