Mrazek, who has three NHL shutouts, has gone 7-2-0 with No. 1 goalie Jimmy Howard out with a groin injury.
"It was a tough last two or three minutes when it was 6-on-5," Mrazek said. "They were in our zone a lot, but I don’t think I had a lot of shots there, maybe three or four. We scored two empty-net goals, so that was great."
Avalanche goalie Semyon Varlamov made 26 saves before he went to the bench for an extra skater with 3:08 to play.
"Tonight's a big night for [Mrazek]," Red Wings coach Mike Babcock said. "The guy at the other end is a star, he's a heck of a goalie. For a kid, it was good for him."
The Red Wings (30-12-9), who have gone 8-1-0 in their past nine games, hadn't played since a 4-1 win Saturday against the New York Islanders and looked rusty early.
"We expected that," Babcock said. "We’ve been off a few days and here it's always tough the first 10 minutes (because of the altitude). It seems like you can’t skate. We couldn’t skate and they could. I thought we really took over in the second period.
"Mrazek was really good off the start, and once we got skating I thought we controlled a lot of the play. We had a good night from a lot of the guys in the last 40 minutes."
The Red Wings used the NHL's top-ranked power play to take a 1-0 lead at 13:25 of the second period. Abdelkader's 12th goal of the season was his first in 10 games. He received a pass from Henrik Zetterberg and stickhandled in front of Varlamov before sliding the puck between his pads. Zetterberg's assist gave him 11 points (five goals, six assists) in his past seven games.
"Varlamov, he really takes away a lot of the net," Abdelkader said. "The puck kind of laid down there in front and went through the legs. I think our power play has been good. We're really doing a good job of breaking down the penalty killers and getting back those second and third chances. Even our penalty kill tonight was huge."
The Red Wings killed two Avalanche power plays in the first period and one in the second. Colorado has gone 22 consecutive power plays without a goal.
"We put pucks on net on the first two, but we just can't get the rebounds," Avalanche coach Patrick Roy said. "We just don't compete enough. The battles in the corner in the second [period], we lost the momentum on that power play because we lost every battle. They clear easy.
"I guess we're going to have to rethink about the players we're going to put on the ice and we're going to have to maybe do things a little different. We've been giving them a lot of chances to produce and it's not working. Zero in 22, that's not acceptable to me. Tonight it was a difference-maker. They scored on their power play and we could not score on ours."
The Avalanche (22-19-11) were 3-0-1 in their previous four games and had won four consecutive home games.
"We skated extremely well in the first period," Avalanche left wing Alex Tanguay said. "We had some chances we have to take advantage of and we didn't, and they took care of their power play and we didn't take care of our power plays. It's very frustrating. Those are points we needed bad."
O'Reilly took a shot Mrazek deflected into the air and Holden knocked it down with his glove. The puck hit Red Wings defenseman Kyle Quincey's skate and Landeskog shot it inside the left post. The Red Wings never had possession before Landeskog's shot, therefore the goal was wiped out.
"It was the right call," Roy said.
Mrazek made 12 saves in the period, four on Avalanche power plays.
"We knew they were going to come hard in the first," he said. "I think they’re ninth in their conference, so they need the points. We knew they were going to come, but the guys did a great job in front of me.”
"I think it was a head shot in the corner," Roy said. "I think that's what started everything. Obviously I'm not in favor of seeing Nate fighting, but I guess he had his reasons. Was that a smart thing to do? I don't think so, but it's an emotional game and you want to set the tone. I respect what he did."
Babcock was also surprised to see MacKinnon drop the gloves.
"I couldn’t understand what happened," he said. "I knew [Ericsson] hit him, but I didn’t expect MacKinnon to be fighting. You’ve got to give the kid credit, he stood up for himself."