The Capitals have excelled on special teams with the NHL's best power play and an excellent penalty kill. The Avalanche have enjoyed most of their success in even-strength play with the league's third-best 5-on-5 goals for/against ratio of 1.70.
A home win Sunday night for the Avalanche would complete a two-game season sweep of the Capitals and extend their winning streak in the series.
Colorado (13-2-0) has won the last three meetings, including a 5-1 victory Oct. 12 in Washington. It was the Caps' most lopsided loss this season, despite a 41-28 edge in shots.
The win followed a 6-4 home loss to Nashville on Wednesday.
"This was a big game for us. After going 12-1, you lose a game, it would be easy to go into bad habits and lose some," Colorado goaltender Jean-Sebastien Giguere said. "We ended up getting a big win. We should be happy with this one."
Giguere made 30 saves and improved to 5-0-0 with a .970 save percentage. He and Varlamov have combined for a 1.79 goals-against average and .944 save percentage.
Stastny's power-play tally was his fifth goal in five games after he scored only one in his first 10. It was also the team's first power-play goal in five games.
Duchene's empty-netter was his team-leading 11th goal and gave him nine points in his last six games.
The Capitals (9-7-1) scored three second-period goals and had a two-goal lead late in the third Saturday at Phoenix before falling 4-3 in a shootout to snap a four-game win streak.
"We got a point, I'm sure we're not happy right now, but we'll just recharge it for tomorrow," Washington coach Adam Oates said.
They entered the game a league-best 10 of 14 in shootout attempts but didn't put either shot on net against Phoenix goaltender Mike Smith. Three of their last four have ended in a shootout, and the Caps are 4-1 this season in games reaching that stage.
Troy Brouwer and John Carlson each scored with the advantage to bump Washington's already stellar power play to 28.2 percent.
Phoenix became the first team this season to score multiple power-play goals on the Capitals, going 2 for 6 after Washington came in having killed 56 of 62 chances.
"Too many penalties just in general," said Oates, whose team lost its lead while short-handed in the final 2 minutes. "You know it's going to come back and bite you and it did."
Three-time Hart Memorial Trophy winner Alex Ovechkin has only one goal in seven career games against Colorado, failing to score in the last six. He's scored at least two goals against every other team in the league.