Without five of their veteran players -- Zdeno Chara, David Krejci, Brad Marchand, Adam McQuaid and Kelly -- in the lineup due to injuries, the Bruins had their three-game winning streak snapped as they lost to the Canadiens 2-0.
After the loss, Bruins coach Claude Julien said he does not know the extent of Kelly's injury, or how long he will be sidelined.
"I could say day-to-day, but we don't know, we don't know right now," Julien said. "And our medical staff has not given me any indication of how long the injury is going to take. It's one of those that I think they've got to feel as the days go by."
As a result of Kelly's injury, rookie Matt Lindblad was recalled from Providence on Saturday morning and was in the lineup against the Canadiens. After placing Marchand on injured reserve retroactive to last Sunday, the Bruins also called up Jordan Caron, who was a healthy scratch against Montreal.