The Capitals have a 2-0 lead in this series, which shifts to Carolina for the next two games, starting Monday. Orpik's game-winner was just his fourth goal in 151 NHL playoff games.
His timing was perfect on Saturday as Evgeny Kuznetsov found him from behind the cage coming off the bench, and Orpik got an opening because the Carolina player defending him didn't have a stick. He then fired a shot past goalie Petr Mrazek (29 saves).
Washington took a 3-2 lead when Tom Wilson took an Alex Ovechkin pass and scored 8:55 into the third period. But the Capitals couldn't hold it as the Hurricanes' Jordan Staal redirected a Dougie Hamilton shot past Braden Holtby (25 saves) with five minutes left for a game-tying power-play goal that tied the score at 3 and forced overtime.
Craig Smith scored at 5:00 of overtime in Game 2 as Nashville defeated visiting Dallas.
Rocco Grimaldi also scored for the Predators, who evened the first-round Western Conference playoff series at a game apiece. Game 3 is scheduled for Monday night in Dallas. Goaltender Pekka Rinne made 22 saves.
Jamie Benn scored the lone goal for the Stars, who won 3-2 in Game 1 and were looking to return home with a two-game edge. Goalie Ben Bishop stopped 40 of 42 shots but suffered the first overtime playoff defeat of his career after five straight wins.
Brad Marchand had a goal and an assist, and Boston defeated visiting Toronto to even the best-of-seven, first-round playoff series at 1-1.
Charlie Coyle, Danton Heinen and Patrice Bergeron also scored for the Bruins. Nazem Kadri scored for the Maple Leafs in the third period but slightly more than three minutes later was given a game misconduct and a cross-checking penalty.
Boston goalie Tuukka Rask stopped 30 shots. Frederik Andersen made 37 saves, several spectacular, for the Maple Leafs.