CALGARY, Alberta (AP) Max Domi's teammates had luck scoring with perimeter shots, so he took his chances in overtime.
Domi fired a low slap shot from just above the left faceoff circle that eluded Riitch's glove on the far side at 3:52 of the extra period.
''I was absolutely out of gas to be honest,'' Domi said. ''The shift before that we were dancing around pretty good and didn't score. They had a chance, Price made a save and he just kind of kicked it out to me.
''I know Gio a little bit from back home. I know how good he is. I'm a big fan of him. He's one of the best defenders in the entire league.
''I knew I wasn't going to beat him at the end of a shift like that. Just figured I'd shoot it through him and got lucky with the shot.''
Nick Suzuki pulled the Canadiens even at 3 with 9:02 left in regulation, deflecting Nick Cousins' pass over Rittich's head.
Carey Price made 24 saves, and Brendan Gallagher and Joel Armia added goals to help Montreal improve to 4-1 in its last five and 17-12-6 overall.
Matthew Tkachuk and Elias Lindholm each had a goal and an assist for Calgary. Oliver Kylington scored his first of the season, and Johnny Gaudreau had two assists. Rittich stopped 39 shots.
Tkachuk and Lindholm scored for Calgary in the first period, and Gallagher and Armia countered for Montreal in the second.
Calgary is 7-3 under interim head coach Geoff Ward, but has lost three in a row.
''We knew they were going to shoot pucks from everywhere,'' Ward said. ''Tonight they got pucks to the net and they got a couple big goals. They got one to get them going and they got one to tie it.''
NOTES: Canadiens captain Shea Weber extended his points streak to five straight game with an assist . . . The Flames wore retro white jerseys, with Rittich donning brown throwback pads and gloves. The Habs suited up in their classic reds.
Canadiens: At Edmonton on Saturday night.
Flames: At Dallas on Sunday.
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