Duchene damaged the medial collateral ligament when he ran into a teammate on the opening shift against San Jose over the weekend. He is expected to miss about four weeks.
The loss is a big blow for the Avalanche, who have turned things around in coach Patrick Roy's first season in charge and are in the running for home-ice advantage with eight games remaining.
''We hope for a speedy recovery to be back as soon as he can,'' Ryan O'Reilly said after practice Monday.
Duchene was trying to avoid a collision with teammate Jamie McGinn, but they awkwardly bumped near the Sharks blue line. Duchene fell to the ice and then gingerly skated to the bench.
''One of those freak accidents in hockey,'' McGinn said.
McGinn said he has called and texted Duchene, telling him to ''stay positive.''
Duchene posted on his Twitter account Monday that the ''thought of not playing in the first round for me has been devastating.'' He added that he will be ''doing everything in my power to be ready for Game 1 ... and if not then, shortly after!''
The 23-year-old Duchene has set career highs this season in points (70), assists (47) and shots (217). He missed three games earlier this season with an oblique injury. The team went 3-0 in his absence.
For now, Roy said the plan is to move rookie Nathan MacKinnon to center to fill in for Duchene, with O'Reilly and McGinn playing on the wings.
''We've been finding ways to win games,'' Roy said. ''We'll continue to find ways to win.''
Here's an encouraging sign: P.A. Parenteau, who sprained his knee on March 10, briefly skated on his own Monday. Roy said Parenteau could possibly be back for the regular season finale in Anaheim on April 13.
''We have depth and a lot of confidence in our players,'' Roy said. ''Our players have a lot of confidence in themselves. It's a team concept. It's how we've been winning our games. It's not going to change.''
Right after practice, Roy assembled his team at center ice, just to give them one final pep talk before taking off for a game in Columbus on Tuesday. He told them he was ''proud of them'' and that the team shouldn't be satisfied, especially with Colorado trailing Central Division-leading St. Louis by only seven points.
The message was well received.
''All year, guys have stepped up and done a great job,'' McGinn said. ''We just stay positive and work hard and good things will happen.''
Asked if there was any pressure stepping in for Duchene, MacKinnon responded, ''No.''
''I'm not going to try to replace Dutchy, because you can't,'' said MacKinnon, a favorite for rookie of the year. ''Matt is a big-time player and we're going to have to find ways to win without him.''
Roy knows all about missing an integral player for the postseason. He and the Avalanche were without Peter Forsberg during their 2001 Stanley Cup run when Forsberg had to have his spleen removed following the Western Conference semifinals against Los Angeles.
The team carried on without the Swedish star, beating the New Jersey Devils in Game 7 to win the title.
''That's the way it was in 2001 - it was about the team,'' Roy said. ''Peter was a very important player on that team, don't get me wrong. But our culture was we had to work hard every time we were on the ice. We had to find ways to win hockey games.
''That's what this team has been doing all year. This is what we're talking about when you're talking about a team changing their culture. We're not looking for an excuse. We're looking for a solution.''