Callahan skated with the team in the pregame warmups at Madison Square Garden on Saturday. And the Lightning announced about 20 minutes before the opening faceoff that he would play against his former teammates.
Callahan had surgery Monday night after experiencing abdominal pain. He was released from the hospital Tuesday, hours before the Lightning beat the Canadiens to advance to the conference final.
Callahan skated on Thursday and Friday.
Former Rangers forward Brian Boyle was scratched from the Tampa Bay lineup with an unspecified injury. He is day to day.