"He just shot low blocker and scored," Vegas goalie Marc-Andre Fleury said. "It was fun. The atmosphere was good. It was such a close game. It was exciting, exciting to be part of, but disappointing to come out on the losing side."
WATCH: [All Golden Knights vs. Avalanche highlights]
Carl Soderberg scored, and Semyon Varlamov made 39 saves for the Avalanche (41-26-8).
Jonathan Marchessault scored, and Fleury made 29 saves for the Golden Knights (47-21-7), who could clinch a berth Saturday if the St. Louis Blues lose to the Columbus Blue Jackets in regulation and the Los Angeles Kings lose to the Edmonton Oilers in regulation.
Vegas is in first place in the Pacific Division, six points ahead of the second-place San Jose Sharks.
"I don't know if it was a playoff preview, but it was a good game," Golden Knights coach Gerard Gallant said. "The first half, they were dominating us. The second half, I think we took over, especially in the third."
The teams play each other again Monday at Vegas.
Varlamov played in his 20th consecutive game (18 starts) after allowing five goals on 20 shots Thursday in a 7-1 loss to the Los Angeles Kings.
"I feel pretty good. What can I say?" Varlamov said. "I'm going to feel even better if we make the playoffs. That's why we're here, we want to make the playoffs. That's why we're battling every game.
"Fleury played an outstanding game. We had moments when I thought the puck would go in, but somehow he stopped the shots, he'd make that big save. That's why he's different than anybody else. In a key moment he can make that save. That was a fun game to play against him, a great goaltender."