Ovechkin ran his goal total this season to 30. He is second to Atlanta's Ilya Kovalchuk, who scored his 32nd goal Saturday night against Boston.
Washington needed Ovechkin's scoring burst after blowing a 5-2 lead early in the third. Michael Nylander scored twice and Ovechkin scored the game's final goal into an empty net with about 28 seconds left.
Alexander Semin had a goal and two assists and Olaf Kolzig made 16 saves, but yielded six goals for the Capitals, who had lost four of their previous five games.
Ottawa got a hat trick from Mike Fisher in a four-goal third period. Daniel Alfredsson scored twice and Jason Spezza once.
Net-minder Martin Gerber was beaten seven times on 29 shots for the Senators, who had won nine of 10.
On the power play, both clubs went 2 for 6.

