One of Ovechkin's two goals was actually a pass attempt that got deflected into the net, but the Capitals captain has five goals in seven games, a further sign that he is emerging from the spotty play that has run parallel to Washington's slow start. The former two-time NHL MVP has 14 goals on the season.
Nicklas Backstrom also scored his 13th of the season - his 100th career NHL goal - for the Capitals. Alexander Semin had a pair of assists for his second multipoint game in a row.
Jochen Hecht scored for the Sabres. Ryan Miller made 18 saves.
The Capitals have had two of their most deflating performances in Buffalo this season, losing 5-1 in the last game before coach Bruce Boudreau was fired.
They then fell behind 4-0 in a 4-2 loss on the day after Christmas, showing they still have a ways to go before getting a consistent rhythm under new coach Dale Hunter.
The Capitals came home from Buffalo to play perhaps their best game of the season, Wednesday's 4-1 win over the New York Rangers.
Washington and Buffalo have been hovering close to each other in the bottom half of the Eastern Conference standings, but the Capitals have pulled three points ahead of the Sabres and have won seven of 14 under Hunter.
The game was only 27 seconds old when Mike Weber was whistled for a boarding call for a nasty hit on Jason Chimera. Ovechkin capitalized on the ensuing power play, albeit purely by accident, when his cross-ice pass to Brooks Laich was deflected by Christian Ehrhoff toward the net, catching Miller off guard.
Washington's second goal featured crisp passes in the offensive zone that went from Ovechkin to Roman Hamrlik to Semin to Backstrom.
The Capitals outshot the Sabres 11-2 in the first period, but the Sabres gained momentum in the second and scored when Hecht put in a rebound off a shot by Thomas Vanek. Buffalo outshot Washington 15-6 in the period.
But Ovechkin put the game away with a one-timer from high in the slot from a feed by Backstrom with 5:50 remaining in the third.
Notes: The Capitals have even more reason to be excited about 2010 first-round Yevgeni Kuznetsov after the Russian captain had three goals and three assists in a 14-0 win over Latvia at the world junior hockey championship in Canada on Thursday. Kuznetsov plays in Russia's Kontinental Hockey League. ''He should here next year,'' Washington general manager George McPhee said. ''He's ready to play here, and he needs to be in a better league.'' ... Buffalo D Andrej Sekera missed his first game with an upper-body injury that is expected to sideline him for weeks. He was replaced by Marc-Andre Gragnani, who had been a healthy scratch for the past four games.