Bednar said that Rantanen will be reevaluated early next week.
"Just see how he progresses over the next few days I think is a big thing," Bednar said. "I can tell you I don't think it is going to be a 4-to-6 week injury, we are hoping he is going to be back significantly sooner than that. But we are just going to have to watch it and see, see how he is feeling in a couple days and what type of workouts he is going to be able to do. Just see how he responds to some of the extra work that he gets off the ice to start and then on the ice as well."
The Nousiainen, Finland, native is tied with Nathan MacKinnon for the team lead with 12 points (five goals, seven assists) through the first nine outings of the campaign. Rantanen is also tied for the league lead with two game-winning goals.
"You lose a guy in the middle of a game and he leaves and your mind starts thinking the worse, but I think as of now to be reevaluating him again early next week and see how he responds to some of the treatment and what not I think it's a positive for sure," Bednar added. "We are at a point in the season where we want him to come back fully healthy, but we don't want him to be out too long either so there is going to be a little bit of a balance there."
Rantanen, who will turn 23 years old on Oct. 29, posted a career-high 87 points (31 goals, 56 assists) in 2018-19. He surpassed the 30-goal mark for the first time in his career and became the second player in Avalanche history to score 20-plus markers in each of their first three NHL season (Chris Drury, four times).
Since joining the Avalanche's roster full-time on Oct. 28, 2016, Rantanen has appeared in 239 of a possible 250 NHL contests. He missed the final eight contests of the 2018-19 campaign with an upper-body injury, but the team went 5-1-2 over that span.
"He is one of the best players in the NHL. When you lose one of the best players in the NHL its tough," MacKinnon said of Rantanen. "We're not going to replace him, but he got hurt last year and we found a way to get some wins. Hopefully we can weather the storm until he gets back. Mikko is a freak, he will be back I'm sure sooner than later and like I said we need guys to step up, including myself."
The right wing has appeared in 248 contests since being drafted No. 10 overall by Colorado in 2015. He has recorded 85 goals and 136 assists for 221 points in his career.
The Avalanche has its second back-to-back set of the season this weekend. Colorado concludes a six-game road trip at the Vegas Golden Knights on Friday before opening a three-game homestand on Saturday against the Anaheim Ducks.