Calgary's third win in a row comes on the heels of back-to-back victories over the weekend against the red-hot Dallas Stars and Western Conference-leading Vancouver Canucks.
After a 37-day stay in 14th place in the Western Conference, the Flames leapt over both the St. Louis Blues and Columbus Blue Jackets and moved within six points of Colorado and Chicago, who are tied for seventh and hold down the final two playoff spots.
Calgary has gone 9-3-3 in its past 15, a stretch that began with a shootout win over Dallas on Dec. 23.
"We've still got to jump a bunch of teams here so there's a long way to go, but the positive thing is we are playing better hockey, we're playing more complete games, and it's adding up to some wins," said Brendan Morrison, who has scored in three straight games and has eight goals on the season.
Nashville, which entered the night having won 10 of its last 12, remained in fourth place in the West, just eight points up on the Flames.
"You have to tip your hat to them when it's deserved and they played very well tonight," said Nashville defenseman Cody Franson. "Kiprusoff played really well and they played a great team game, it was tough for us to generate anything."
Leading 2-1 in the third and with Nashville pressing, Morrison scored the prettiest goal of the night at 14:08, converting Tanguay's perfect pass.
It was the second power-play goal of the night for the Flames, who last scored two power play goals in a win over Toronto on Dec. 16. Coincidentally, that was the last time Calgary was higher than 14th place.
"When you lose, it's almost like you don't want the puck," said Tanguay. "Right now everybody wants it, it's very contagious and hopefully we can keep on working the same way and keep on getting better."
Calgary's 26th ranked power play finished the game 2-for-6 against the NHL's third best penalty killing unit. Nashville went 0-for-5 with the extra man.
"We have confidence right now, we are moving the puck extremely well," said Tanguay, who in the last couple games has been playing the point on the power play alongside Mark Giordano.
With the game tied 1-1, Iginla gave Calgary the lead at 13:01 of the second. Tanguay's slap shot was stopped by Rinne but Stajan slid the rebound to a wide open Iginla, who buried his team-leading 21st goal.
Kiprusoff was pulled twice in his previous four starts before turning in a 41-save performance Saturday night in the Flames' 4-3 shootout win against the Canucks.
The 34-year-old Finn was solid again versus the streaking Predators, saving his best work for the third period as Nashville peppered him with 11 shots.
"He's bounced back huge for us. He played great in Vancouver, made some huge saves to keep us in that game and tonight, he made some difficult saves look easy and that's what he does when he's on his game," Morrison said.
Tanguay said the team never lost confidence in him despite the rough patch.
"Obviously, when you're the goalie, your mistakes show a little bit more than anyone else on the team but we've got confidence and in order to get where we have to, we need him to play well and we have full confidence he's going to do that," Tanguay said.
Calgary scored the lone goal of the first period at 10:14.
From the side of the Nashville net, Glencross had his shot deflect off a stick and loop up in the air and over a helpless Rinne.
Legwand tied it at 10:32 of the second.
The Predators dropped to 3-2 on a season-high six-game road trip, which wraps up in Vancouver on Wednesday.
"Our penalty kill wasn't good enough tonight and either was our power play and that was the difference," said Predators defenseman Shane O'Brien.
It is just the second time in his last 11 starts that Rinne has given up more than two goals. He's 9-2-0 during that span.
Material from wire services and team media was used in this report.