Carl Hagelin scored a pair of third period goals against his old team as the Capitals beat the Penguins 5-3 in Washington.
Evgeni Malkin had a goal and an assist for Pittsburgh, which dropped its third straight game.
Sidney Crosby and Patric Hornqvist also scored for the Pens.
The Penguins will be on the road Wednesday as they visit the Kings in Los Angeles.
They sit just two-points out in the Metropolitan Division with 80 points at 37-18-and-6.
(Photo by Patrick Smith/Getty Images)