MacKinnon trimmed the lead to 5-2 at 3:08 when he chipped a shot over Markstrom's glove on a breakaway, and Valeri Nichushkin finished a give-and-go with Mikko Rantanen for a power-play goal to make it 5-3 at 11:01.
"It's their home opener so you know they're going to come out with a lot of juice, and they brought it to us," Colorado forward Evan Rodrigues said. "I think once we simplified the game and not try to be too cute with it, that's when we started to have success in the third. But it was just too little, too late."
NOTES: Dube has nine goals in his past 10 regular-season games dating to last season. ... Rantanen has five assists in two games to start the season. ... Weegar played 20:43, Huberdeau played 17:11 and Kadri had 17:43 of ice time. Each did not have a shot on goal. … Weegar is the fifth defenseman to have multiple points in his Flames debut, following Phil Housley (three points, Jan. 20, 1995), Mark Cundari (two, April 21, 2013), Steve Chiasson (two, Jan. 20, 1995) and Mark Ramage (two, March 9, 1988). … Backlund played his 827th game to move past Robyn Regehr for third in Flames history behind Jarome Iginla (1,219) and Mark Giordano (949). … Sutter is 700-503-94 with 101 ties in 1,398 games in 20 seasons with the Flames, Blackhawks, San Jose Sharks and Los Angeles Kings.