David Pastrnak, the Boston Bruins' 2014 first-round draft choice, left the ice and didn't return after he went into the boards during a drill about a half-hour into a scrimmage Saturday.
Pastrnak was able to skate off the ice and into the dressing room on his own.
"Tweaked his shoulder," Bruins coach Claude Julien said following the practice at Ristuccia Arena. "So I don't know how serious it's going to be, but very, very doubtful for tomorrow."
"I would think, if anything, he'll be stiff and we wouldn't take that chance, but I don't think it's too, too serious."
Tyler Randell took Pastrnak's place on the right side with Matt Fraser on the left and David Krejci in the middle.
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