Mason turned aside all 25 shots he saw, including 14 in a hectic third period, backstopping the Jets to their first victory in three games against the Senators this season.
Jim Slater scored 49 seconds into the game, giving the Jets an early lead, and Tobias Enstrom added an insurance tally in the second period as Winnipeg won for only the third time in seven games overall.
Craig Anderson made 33 saves for the Senators, who had a four-game winning streak snapped.
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