The teams were tied 2-2 after two periods and didn't score in the third or overtime.
Spezza, who scored the lone goal in Ottawa's win Saturday against Toronto, stopped at the circle during his shootout attempt, stickhandled around goalie Jeff Zatkoff, and scored. Kyle Turris added a goal in the shootout for the Senators.
Turris scored his 26th goal in regulation, and Mark Stone had his fourth for Ottawa, which will miss the playoffs for the second time in six years and first since 2011.
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