Alex Ovechkin and Devante Smith-Pelly also scored for the Capitals, and Pheonix Copley stopped 24 shots.
Colin Wilson and Carl Soderberg scored for the Avalanche while Grubauer, acquired by Colorado in an offseason trade with Washington to bolster their depth at goalie behind Semyon Varlamov, had 26 saves.
With 2:44 left in the third period, Ian Cole fired a shot from between the circles that glanced off Copley’s pads. The puck trickled out to the right side of the net, where Wilson tied it at 2.
The Capitals ended it on a 4-on-3 power play. Backstrom was left uncovered for a clean shot in the high slot that beat Grubauer on his stick side. Backstrom also had an assist.
“We drew a penalty and made the most of our chance,” Ovechkin said.
Avalanche coach Jared Bednar said he thought the Avalanche did not play with a sense of urgency early.
“Third period, different story,” he said. “We started ramping it up, that’s why we generated some chances in the third and they didn’t, because we were more desperate. I want us to play a whole game like we’re down a goal and bring that desperation and urgency to the game.”
With the score tied at 1, Tom Wilson started a rush and passed the puck ahead to Backstrom, who dished off to the streaking Ovechkin. He split defenders and let loose a wrist shot from the top of the right circle that sailed over Grubauer’s glove at 18:29 of the second.
Smith-Pelly pulled Washington Even 8:55 into the second off a cross-ice pass from Chandler Stephenson.
Colorado just missed adding a goal from Mark Barberio when his shot glanced off the right post at 11:01 of the second.
“A sloppy game by us,” Colin Wilson said. “They had more effort, a little more attention to detail. We turned it on in the last 10 minutes, but it was just too little, too late. Games like that, you want to eliminate them as much as possible. It wasn’t an X’s and O’s thing, just effort.
“Coming out with a point is better than no points at all,” Wilson added.
NOTES: T.J. Oshie, Evgeny Kuznetsov and Braden Holtby were ruled out for the game against the Avalanche because of upper body injuries. They are all listed as day to day. … The Avs remain one win shy of their 1,000th victory since moving to Denver from Quebec in 1995. The Avs 999 wins in that span include 897 in the regular season and 102 in the playoffs.
Capitals: Play at Montreal on Monday night.
Avalanche: Visit Anaheim on Sunday night.
More AP NHL: https://apnews.com/NHL and https://twitter.com/AP_Sports