"Peter Regin's season is likely over.

The Senators centre wasn't on the ice Thursday morning at Scotiabank Place after his surgically repaired left shoulder stiffened up and he's going to have to decide whether he's going to have another procedure to get it repaired.

Regin won't be in the lineup against the Florida Panthers and he's out indefinitely.

Winger Bobby Butler returns and defenceman Brian Lee will be in the lineup with the club carrying seven blueliners.

"It happened during the game (Tuesday) and it stiffened up on him," said coach Paul MacLean Thursday."