BOSTON — Bruins fourth-line center Gregory Campbell is doubtful for the Oct. 8 season opener against the Philadelphia Flyers at TD Garden.

“He started skating this (Thursday) morning. I don’t know where he stands,” B’s head coach Claude Julien said after practice. “He’s skating right now, he just started skating on his own.

“I think he will be doubtful to start the season because starting to skate and getting into practices, and full contact and game shape is going to be a little tough for him in a short span. The good thing is he’s skating, and hopefully he progresses in the right direction.”

Campbell has a minor mid-core injury and hasn’t participated in a training camp practice or one of the five preseason games so far. If Campbell doesn’t play in the opener, veteran Chris Kelly and forward prospect Craig Cunningham are the best options for the fourth-line center spot.

Campbell tallied 21 points (eight goals, 13 assists) in 82 games last season.