Nathan MacKinnon had a big game Saturday night, factoring in all three of the Avalanche’s goals, but most of his teammates struggled and the Dallas Stars emerged victorious in Game 1 of a Western Conference semifinal series at Rogers Place.

The Stars’ Alexander Radulov matched MacKinnon with two goals and Dallas played a better north-south game in winning 5-3 at the Edmonton bubble. The Avs, who lost starting goaltender Philipp Grubauer to injury early in the second period, faced a team playing a mirror-image of how they like to play — fast and always trying to create a counter-attack off turnovers.

But Colorado made too many mistakes in the defensive zone and neutral zone to expect to win and only drew two penalties and had just one power play.

“I think they came out flying and put us on our heels a little bit and we didn’t respond the way we needed,” MacKinnon said. “You prepare, you video on the other team, you’re so focused on them, maybe you forget the way (we play). We can video on them all we want but we have to play our game if we’re going to win. Tonight, they came out harder than us. They seemed like they were more competitive than us. There is no excuse for that.”

The Avs were without key winger Matt Calvert (not fit to play) and lost Erik Johnson to injury during the game and the veteran played just a little more than 10 minutes.

Grubauer suffered what appeared to be a leg injury 3:06 into the second period and was replaced by Pavel Francouz, who inherited a 3-1 deficit. Grubauer leaned to his right to stop a shot that wouldn’t have hit the net and fell face-first to the ice. He was helped off the ice by a trainer and teammate, unable to put weight on his left leg.

“It (stinks) seeing guys go down,” Avs captain Gabe Landeskog said. “Everybody that’s in that lineup is there for a reason and when guys go down there is a hole to fill, but it’s the next-man-up mentality and it’s no bigger deal than that.”

The Avs entered the third period trailing 4-3 but probably should have been down more than that. Dallas outshot Colorado 24-23 at that point and often controlled the pace — the way the Avs usually play.

“We had half our team not show up to play,” Avs coach Jared Bednar said. “When it comes down to it, they were, as a team, engaged, ready to go. We had a little bit of a slow start and weren’t ready to engage and compete the way we needed to to win the hockey game. I thought we were starting to come for a while, but we weren’t. That was just our big guys playing. Obviously, our big guys had a good night. They were here to compete, to play to win the hockey game, and we had a lot of guys that weren’t. And when I say ‘a lot,’ I’m talking half our team.”

The Stars got two goals from Radulov and one apiece from Tyler Seguin and Blake Comeau in building a 4-2 lead. But the Avs cut two two-goal deficits in half with goals from Gabe Landeskog and MacKinnon, the latter with a redirect in front of the net late in the second period.

Landeskog made it 3-2 with a skilled wrap-around from behind the goal line for his first goal of the playoffs. MacKinnon assisted on that goal and then scored his second of the game for his NHL-leading 16th point of the playoffs. MacKinnon extended his points streak to nine games, the second-longest streak to begin the postseason in Avalanche history (Joe Sakic, 10 in 1996).

Footnotes. Trade-deadline acquisition Michael Hutchinson is Colorado’s third-string goalie and the team’s only other goalie in the Edmonton bubble. … Calvert, the veteran fourth-line forward and leader, was “unfit to play” and scratched from the lineup. Johnson walked gingerly to the dressing room twice after two collisions. Johnson ed from the bench during the third period but didn’t play. … Winger Vladislav Namestnikov returned from a four-game injury and replaced Calvert.