Hampus Lindholm's power-play goal broke a 1-1 tie with 5:56 left in regulation to lift Anaheim past Colorado at Pepsi Center.
Devante Smith-Pelly also scored on the power play for the Ducks, who went 2 of 7 with the man advantage.
"I think both of their goals were power play goals, and both of them we had a chance to clear which we didn’t," said Avalanche center Paul Stastny. "I think we are just getting the rustiness out. We learned so much the last couple of days, so we are trying to get in the groove of things."
John Gibson earned the victory by stopping all 18 shots he faced in relief of Frederik Andersen, who made nine saves.
Semyon Varlamov stopped 22 of 24 shots for the Avs.
Colorado had several players who saw their first NHL action, including defenseman Chris Bigras, who signed his first professional contract the day prior.
“It felt good to get the first one under the belt – there was a little bit of nerves coming in because it was the first time," Bigras said. "As the game goes on, you start to feel comfortable.”
Stastny said the players that saw their first action will now be more comfortable in playing in an NHL game in the future.
"Next time they get out there they’ll be less nervous now that they have that under their belt and they know what it’s like playing at NHL speed," he said.
The Avs continue its preseason schedule on Friday as they host the Los Angeles Kings. Colorado and Anaheim will open the regular season against one another in Denver on Wednesday, Oct. 2.