DENVER -- Four regular Colorado Avalanche defensemen have been ruled out for Tuesday night's game against the Calgary Flames at the Pepsi Center.

Coach Joe Sacco revealed following Tuesday's morning skate that Kyle Quincey suffered a concussion, presumably in Saturday's 5-0 win over Dallas. Quincey becomes the fourth Avalanche player currently sidelined with a concussion, joining fellow defensemen Kyle Cumiskey and Adam Foote, and forward Peter Mueller.

"No idea, just one of those things, part of the game," Sacco said when asked about the rash of head injuries. "I can't put my finger on the reason why."

With Cumiskey, Foote, Quincey and Ryan Wilson (leg injury) unable to play, rookies Colby Cohen, Jonas Holos, David Liffiton and Kevin Shattenkirk will be on the blue line against the Flames. They'll be joined by veterans Scott Hannan and John-Michael Liles.

Cohen (two games), Holos (nine games), Shattenkirk (one game) and Liffiton (seven games, three this season) have played a combined 19 games in the NHL.

Sacco said it has been "fun" coaching an Avalanche team that has the youngest active roster in the League with an average age of 25.8 years, and he is willing to accept mistakes as long as he's satisfied with players' work ethic.

"It's a game of mistakes," Sacco said. "Usually the team that makes the fewest mistakes ends up winning. We're a young team and we play with lots of energy and lots of passion. We're going to make our share of mistakes. It's how you respond after you make a mistake. We're patient to a point."

Goalie Peter Budaj will make his sixth consecutive start as Craig Anderson continues to recover from a right knee injury. Budaj is coming off a 31-save shutout against Dallas.

Perhaps the Flames can take advantage of the Avalanche's inexperienced defense corps to get their offense back on track. They've lost four games in a row, totaled four goals in the past three defeats and squandered strong goaltending by Miikka Kiprusoff in back-to-back 2-1 losses.

Calgary also is in a 3-for-20 slump on power plays.

Counting tonight, the Flames will play eight of their next 10 games on the road.

"We're in a position we don't want to be in," Flames left wing Alex Tanguay said of his team's 6-7-0 record. "We don't want to be on the outside looking in. This month is key for us to get ourselves back in that contention pack. We don't want to fall off the pace. We don't want to put ourselves behind the eight-ball. It's a great month to do it, on the road with all the boys together."