Ritchie scored twice and Boyd's first NHL goal with 2:17 left in the game broke a 2-2 tie giving the Flames a 4-2 win over the Dallas Stars.
On the game winner, Andrew Ference's slapshot from the blue-line missed the net but caromed off the boards and out the other side where Boyd banged it in past goaltender Marty Turco from a sharp angle.
"I was just going to the net and hoping for a rebound and it hit the back boards and came right to me and I've got to bury those opportunities," said Boyd, who had two assists in five games with the Flames earlier in the season.
Boyd was one of two forwards called up from Omaha of the American Hockey League on Friday to take the places of Iginla and Chuck Kobasew (concussion), who were both hurt in Thursday night's win over the Florida Panthers.
"With a guy like Iginla out and Chuckie, you can't fill that void completely. You've just got to go out there and make the most of your opportunities," Boyd said.
Tanguay, into an empty net, also scored for Calgary (21-15-4). Tanguay also had two assists. Winners of four of their last five, the Flames move into sole position of second spot in the Northwest Division, one point back of Vancouver.
Daryl Sydor, with his first goal in 34 games, and Jere Lehtinen scored for Dallas (26-16-1). Rookie forward Loui Eriksson had two assists for his first career multi-point game.
While Boyd stepped into one of the line-up openings, Ritchie was promoted to the second line where he played alongside Matthew Lombardi and Alex Tanguay and logged a season-high 17 minutes of ice time.
"It's a huge character win for us. Going into the third period tied at 2-2 against a good hockey team, we just kept plugging away and Boydy got a huge goal for us," said Ritchie.
Ritchie's first career two-goal game gives him six goals on the season, surpassing his previous high of five, which he accomplished while with the Florida Panthers.
"Believe it or not, I used to be a goal scorer," said Ritchie, who scored 50 goals twice in junior but has just 20 NHL goals in 224 career games.
Like the Flames, the Stars iced a depleted line-up without defenceman Sergei Zubov - the latest to land on the sidelines, missing his first game of the season due to back spasms. The Stars are already persevering without captain Brenden Morrow (ankle), Mike Modano (hip), and Eric Lindros (ribs).
Despite the key absentees, Dallas outshot Calgary 33-21 but ran into a familiar nemesis in goaltender Miikka Kiprusoff.
"We had a lot of shots, a lot of opportunities, but he made some big saves again. That's why he's a top goaltender in the league," said Sydor. "We played well for a majority of the game but we needed to play well for a couple more minutes to take it into overtime."
Tied 1-1 after the first period, Ritchie's second of the night gave Calgary its first lead of the night 1:17 into the second. Similar to his first goal, Tanguay spotted an Ritchie open in front of the net for a one-timer.
"When Tangs is throwing you passes right on the goal line, it's hard to miss those," said Ritchie. "It was really enjoyable playing with Lombo and Tangs. They're great players and make it easy for me."
Dallas answered back at 11:15 of the second period, tying it on their second power-play goal of the night on as many opportunities.
"It was a grind tonight and we knew it was going to be like that and when you're that close to getting an extra point, it's a little disheartening," said Turco.
Notes: - Calgary RW Tony Amonte was elevated onto the Flames top line alongside C Daymond Langkow and LW Kristian Huselius... The last game Iginla missed was Jan. 19, 2004. The one game he missed at that time with a sore knee is the only previous time Iginla has missed NHL action with any type of leg injury. Since then, Iginla had appeared in 158 straight games ... The 11 games Iginla missed with a hand injury in 1997-98 (Jan. 24 - Mar. 5, 1998) is the longest stretch of games he has missed in his career... Calgary is unbeaten (4-0-2) the last six games Iginla has not been in the line-up. In the 31 games Iginla has missed in his career, the team is 15-11-5.