Colorado Avalanche star center Nathan MacKinnon will miss approximately four weeks with an upper-body injury, the team announced on Tuesday night.

MacKinnon left Colorado's 5-3 loss to the Philadelphia Flyers on Monday. The veteran forward took a wrist shot from the slot in the first period, and as the puck sailed wide of the net, he winced but remained on the ice and finished his shift. When he went to the bench, the game broadcast showed a shot of him favoring his left side.

"The fact he's leaving early in the game is not a good sign," Colorado coach Jared Bednar said on Tuesday, before learning of MacKinnon's timeline. "We know he's going to miss some time. Just don't know how long."

The defending Stanley Cup champions have been plagued by injuries this season, but MacKinnon has still produced. He heads into his recovery with eight goals and 33 points, and given the lack of depth up front, he is averaging 22:39 time on ice.

Even before the injury, Bednar had already used 22 different forwards in his lineups. After the loss Monday, he made mention of the team's rash of injuries, saying, "this is probably as bad as I can remember."

MacKinnon is coming off a standout season in which he skated in 65 regular-season games, posting totals of 32 goals and 88 points. In the postseason, on the way to the franchise's third title, he had 13 goals and 24 points.

The short-handed Avalanche will enter Wednesday's home game against the Boston Bruins with 13 wins and 27 points. In a clogged Western Conference playoff race, they are tied for the No. 2 slot in the wild-card standings with the Calgary Flames.

"Guys are going to have to step up. It's going to be a challenge," Bednar said Monday. "You've got to go out and play hard every night, regardless of the cards you're dealt."

MacKinnon, 27, the No. 1 overall pick in 2013 and a three-time Hart Trophy finalist, agreed to an eight-year, $100.8 million extension before the season. In the salary-cap era, it was the NHL's richest contract.