After playing three games in four days, the Bruins got a day off on Sunday.

Center David Krejci will have a little more time off than that after being injured in a collision with St. Louis forward T.J. Oshie in Saturday's 2-1 shootout loss to the Blues.

The Bruins announced on Sunday afternoon that Krejci has been diagnosed with a concussion. "He will be out for at least a week and he will continue to be evaluated by our medical team," read the update on the team's media site.

That means Krejci will likely miss at least three games, as the Bruins play at Pittsburgh on Wednesday, then host Montreal on Thursday and Ottawa on Saturday.

Krejci and Oshie collided going for the puck in the neutral zone 44 seconds into overtime, and Krejci took both the worst of the hit and the aftermath as he slammed his head on the boards on the way down. He stayed down for several minutes, but eventually skated off on his own power. He did not return for the remainder of overtime or the shootout and was not available to the media after the game.

The loss of Krejci is a major blow to the Bruins' offense, as the club is already without center Marc Savard, who remains sidelined with post-concussion syndrome symptoms. Krejci has taken over as the Bruins' top center, skating between Milan Lucic and Nathan Horton on one of the league's most productive lines this year.

That trio has combined for 13 goals and 18 assists for 31 points through 11 games, with Krejci tied for second on the team with 2-8-10 totals.

The Bruins have center options in Providence they could turn to in the form of former first-round picks Joe Colborne and Zach Hamill. Colborne has come alive in the AHL after a slow start in his first pro season, but unless Krejci is sidelined much longer than expected, the Bruins will likely go with the options already available on the big club's roster.

Daniel Paille has been a healthy scratch since the second game of the season, while Brian McGrattan has yet to see his first action as a Bruin. Paille would be the likely choice to play against the small but skilled Canadiens on Thursday, where his speed could be an asset.

Likewise, McGrattan could come in handy against Ottawa, which features heavyweight Matt Carkner and tough guy Chris Neil, who drew McGrattan's verbal wrath for picking a fight with Dennis Seidenberg in the clubs' first meeting in Ottawa on Oct. 30.

Either player could be an option for Wednesday's matchup against Pittsburgh. Paille's speed and penalty-killing ability could be useful against Sidney Crosby and Co., while some extra muscle against a Penguins lineup featuring Eric Godard, Michael Rupp, Deryk Engelland and Arron Asham wouldn't hurt, and having another deterrent against cheap-shot artist Matt Cooke is never a bad idea.

Regardless of whom the Bruins insert into the lineup this week, Krejci's absence will force some juggling of the line combinations. Patrice Bergeron could slide into the top-line center spot between Lucic and Horton, with Tyler Seguin and Greg Campbell also moving up the center hierarchy.

Campbell moving up would break up Boston's productive energy line, but Brad Marchand is capable of moving to center on that unit with Shawn Thornton and either Paille or McGrattan. Blake Wheeler could also see some time at center, which would allow coach Claude Julien to keep the fourth line intact. Wheeler played center in college and spent some time in the middle during camp this year.

The options aren't ideal, and the Bruins certainly don't want to be without Krejci for long, but Boston at least can take solace in that fact that they have much better depth than most teams to absorb what they hope will be just a short-term loss.