MONTREAL -- Presented with a plush opportunity on the top line, Colorado Avalanche left winger Mikhail Grigorenko made the most of the promotion.

With captain Gabriel Landeskog sitting out two games due to a suspension, Grigorenko scored a goal and two assists in the first period alone to help lift the Avalanche to a 6-1 win over the Montreal Canadiens on Saturday night at the Bell Centre.

"At the beginning of the season, I didn't really have a good camp but I just kept working hard and Patty (coach Patrick Roy) told me, you've just got to take your chance when you have it," Grigorenko said. "Obviously I've been playing 6-8 minutes and today was more ice time and fortunately I was able to make something happen."

His three points matched linemates Nathan MacKinnon (two goals, one assist) and Matt Duchene (one goal, two assists). Center Matt Duchene and left winger Blake Comeau also scored for Colorado.

Goaltender Reto Berra stopped 39 shots for Colorado (7-9-1), which improved to 3-0-0 on its season-long seven-game road trip. Mike Condon stopped only 7 of 11 shots for the Canadiens (13-3-2) in two periods of work in suffering his first regulation loss of the season. He was replaced to start the third period by Dustin Tokarski, who stopped 11 shots in relief.

"It's a game of mistakes but the mistakes we made were too costly," Montreal captain Max Pacioretty said of his team, which lost in regulation on home ice for the first time this season. "Breakaways, Grade A chances in the slot; you've got to know who you're out there against as well. That top line's had a lot of success lately and we've got to know when we're on the ice against them. You've got to tighten it up a little bit more defensively. They made us pay tonight."

Right winger Brendan Gallagher scored for Montreal.

Grigorenko opened the scoring at 3:26 of the first period. Matt Duchene picked up the puck off the faceoff and skated to just outside the trapezoid before sending the puck to the slot. Grigorenko got his stick on it before turning at the hashmarks and firing home his first of the season.

MacKinnon doubled the Avalanche lead at 18:25 when, off the faceoff, he corralled a loose puck and, uncovered, spun around, from just inside the left circle.

The third-year center made it 3-0 with his second of the night 13 seconds later. Duchene found MacKinnon in the neutral zone before the latter dished off to Grigorenko just outside the Canadiens' blue line. Skating in along the left side, Grigorenko waited before feeding MacKinnon for a nifty backhand from the right of the dot.

After outshooting Colorado 18-8 in the first period, Montreal finally managed to beat Berra at 8:48 of the second period.

Pacioretty sent the puck along the wall to center Tomas Plekanec behind the net. Plekanec waited for an opening before sending it to Gallagher in front, who made the most of the rebound of his own shot to pick up his eighth of the season, tying him for the Canadiens' team lead.

Comeau restored the Avalanche's three-goal lead with a shorthanded tally just over four minutes later. Defenseman P.K. Subban, at the top of the right circle, tried for a backhand pass to Andrei Markov. But the blue-liner wasn't in his spot and Comeau pounced on the loose puck before skating up the right wing and firing a shot from the top of the right circle.

"I thought we were coming back in the second period with that power play but the guy came down" Condon said. "I've got to make that save. It kind of killed momentum for the boys. I've got to take ownership of that. If I make that save, I think it's a different game."

Duchene made it 5-1 on the power play at 11:05 of the third period. Tokarski stopped Mackinnon's shot from the top of the right circle, but an unattended Duchene was there waiting to the goalie's left and roofed it for his team-leading eighth of the season.

Montreal's defensive miscues allowed Mitchell to add to the rout 3:05 later. Tokarski stopped a shot from the right side but couldn't recover after a teammate collided with him and Mitchell, uncovered to the left of the net, easily found the back of the net.

NOTES: Canadiens RW Alexander Semin returned to the lineup after sitting out the last seven games as a healthy scratch while D Greg Pateryn made his season debut in place of D Alexei Emelin, who missed the game with a lower body injury. ... Montreal scratched LW Paul Byron and D Jarred Tinordi. ... Avalanche LW Gabriel Landeskog served the first of a two-game suspensions for a head hit on Boston's Brad Marchand. ... Colorado LW Blake Comeau appeared in his 500th NHL game while D Tyson Barrie suited up for his 200th. ... The Avalanche scratched D Zach Redmond. The game was the Canadiens' 6,500th in team history (NHA and NHL).