OTTAWA - They have survived, even thrived, without important defenceman Jared Cowen.

Now the Senators have to carry on minus their top centre -- possibly, like Cowen, for the rest of the season.

The morning after watching his team improve to 5-1-1 and move to within two points of first in the overall standings by thoroughly pounding the Montreal Canadiens, GM Bryan Murray announced Jason Spezza will have back surgery to repair a herniated disc Friday in Toronto. He is out of the lineup "indefinitely."