When all the sawdust was cleared, they were on the bottom of a 4-3 final, their fourth loss in five games this season.
Ottawa blew a 3-1 lead by giving up a pair in the second and the winner, off the stick of Canadiens centre Tomas Plekanec, with four minutes to go in third.
Plekanec was left alone to whip home a rebound after Brian Elliott had stopped the initial deflected shot.
“It was two different games. We got up 3-1 and completely changed our game, for whatever reason,” said Senators coach Cory Clouston. “I don’t know if we thought it was going to be easy, they were going to just give us the two points ... ”