DENVER -- The Boston Bruins came into Denver tired and nearing the end of a long road trip.

It didn't matter with the dominant season goaltender Tuukka Rask is enjoying.

Rask stopped 21 shots for his third shutout of the season, David Krejci had a goal and an assist, and the Bruins beat the Colorado Avalanche 2-0 Sunday night.

Dominic Moore's empty-net tally with 27.2 seconds left sealed the third straight win for Boston (10-6-0) and gave Rask his 33rd career shutout.

"Just another great game. Can't say enough about that guy," Krejci said of Rask. "He's been great so far and keeping us in the game every single game. Sometimes we only need one or two goals to win."

Rask got the shutout less than 24 hours after making 31 saves in a 2-1 win at Arizona. He told coach Claude Julien after beating the Coyotes he felt good enough to start Sunday, and he proved it to improve to 7-0-0 on the road this season with help from his defense.

"I can't recall any real breakdowns for us," Rask said. "We kept them on the outside and really limited their scoring chances and rushes. And then we kept the puck in the offensive zone and made some plays and created chances."

Rask dropped his goals-against average to 1.54 and upped his save percentage to .945.

"He's been solid since the start of the season and giving us a chance to win every night," Julien said.

Semyon Varlamov had a season-high 43 saves for Colorado, which was shut out for the fourth time in the first 14 games of the season. The 44 overall shots were the most Varlamov faced this season.

"It's frustrating that we didn't win," Varlamov said. "It doesn't matter how you play. I'm not happy that we lost because we need the two points. That's the most important thing for us."

The Avalanche (6-8-0) played without leading scorer Matt Duchene, who was out with concussion-like symptoms after taking a stick to the eye area in the second period against the Winnipeg Jets on Friday.

Duchene will skate at practice Monday, coach Jared Bednar said.

Rask didn't need to work hard to improve to 10-1-1 this season. He faced just 14 shots through the first two periods as his team dominated from the opening faceoff.

Krejci put Boston ahead midway through the first period. He skated in, took a drop pass from David Backes and snapped a shot past Varlamov's stick at 9:30. It was his second goal of the season.

"It was a little bit of a broken play," Krejci said. "I was flying wide and had good speed, kind of read the scouting report on that goalie and tried that shot and happy it worked."

The Bruins dialed up the pressure in the second period but couldn't get a second goal because of Varlamov. The goaltender, who faced only 18 shots while beating Winnipeg, stopped 23 in the second period alone Sunday.

"The second period was where we started not getting out of our zone, made some soft plays and then turned pucks over at the red line," Bednar said. "Varly was outstanding; he was the best player on the ice."

Varlamov's best stop came when he slid over to save Brad Marchand's shot on an odd-man rush with 1:57 left in the second period. The goalie then gloved Marchand's shot off the rebound.

The Bruins got the game's first power play 20 seconds later and put four quality shots on Varlamov, but he stopped all of them.

"We've got to start getting rewarded for that kind of effort and that kind of dominance," Julien said.

Varlamov made a third-period save on Brandon Carlo's breakaway after the defenseman came out of the penalty box.

Colorado pulled Varlamov for an extra skater with 1:06 left, but Moore foiled the strategy with his fourth goal of the season.

NOTES: With C Matt Duchene sidelined with a head injury sustained Friday, the Avalanche recalled LW A.J. Greer from San Antonio of the AHL. Greer, who made his NHL debut Sunday, had five goals and nine assists in 13 games with the Rampage. ... Boston G Anton Khudobin (upper-body injury) is traveling with the team. ... Colorado RW Blake Comeau (groin) missed his fourth consecutive game. Comeau skated Saturday, but there isn't a definite date for his return. ... Avalanche D Fedor Tyutin was in the lineup despite an arm injury. ... Bruins rookie D Brandon Carlo is from Colorado Springs, Colo. He played as a professional for the first time in his home state.