Avalanche coach Patrick Roy said Duchene will have an MRI on Sunday.
"He's playing so well right now," Roy said. "It's not good news for him and it's not good news for us as well, but it's been the way it's been all year. We always try to win hockey games and we're going to have to continue to find ways to win hockey games."
Colorado's 3-2 win clinched its first berth in the Stanley Cup Playoffs since 2009-10.
"I'm always a positive person. I believe that he's going to be back for playoffs," Roy said of Duchene. "At the same time, we lost Peter Forsberg after the second round the year we won the Stanley Cup (in 2001). A team is a team. You have to go out there and play hard and find ways to win games. That's what we're going to continue to do."
Duchene, whose career-high 70 points leads the Avalanche, limped off the ice 32 seconds after the opening faceoff after he collided with linemate Jamie McGinn just across the Sharks blue line.
"It's a significant loss for our team if he's out for an extended period of time, but we've had injuries during the year and we've had plenty of guys come in and step up and fill in roles and we've done OK," said John Mitchell, who replaced Duchene on a line with Ryan O'Reilly and McGinn. "That's going to have to happen again, I guess."
Avalanche captain Gabriel Landeskog said he and his teammates can't use Duchene's injury as an excuse, regardless of how serious it turns out to be.
"He's been playing great, he's one of our best players, but it certainly doesn't change anything or us," Landeskog said. "We've certainly adapted all season with injuries to key players."