Boston Bruins captain Brad Marchand is officially out and "week-to-week" with an upper body injury, interim coach Joe Sacco announced Tuesday.

Marchand missed Sunday's 1-0 loss to the Minnesota Wild one day after being injured on a hit by Pittsburgh Penguins defenseman P.O Joseph, with Marchand's head hitting the boards. After receiving attention from a trainer for several minutes, Marchand was helped from the ice.

Sacco would not specify whether it was a head injury for Marchand, 36, who has a history of concussions. The winger has 47 points in 61 games this season, second on the Bruins.

"Obviously, a hard guy to replace. We're going to miss him. But it creates opportunities for other guys now to step up," Sacco said.

Georgii Merkulov, a 24-year-old rookie, skated in Marchand's place on Boston's No. 2 line next to Charlie Coyle and Elias Lindholm.

"It's not one guy that's going to come up and be Marchy. No one's going to do that," Coyle said. "He brings so many elements to the game that we're going to miss. So we can all take a piece of that and help out that way."

The timing of the injury couldn't be worse for the Bruins. There was talk that Marchand, in his 16th season with Boston, could be moved before Friday's NHL trade deadline, as he's in the last year of his contract. But the Bruins are also in the Eastern Conference wild-card race, two points in back of Detroit for the final playoff berth, although the Red Wings have two games in hand. Stathletes currently gives the Bruins just a 4.9% chance of making the postseason.

Marchand won gold with Team Canada at the 4 Nations Face-Off last month.

"He's disappointed. Any time a player is injured and misses time, they're disappointed. But he'll be back," Sacco said.