Oshie gave Washington a 1-0 lead at 7:09 of the first period when he redirected Carlson's shot from the point on the power play.
Justin Schultz made it 2-0 at 2:13 of the second period, getting to a rebound at the top of the crease.
"There were two games that were played," Washington coach Peter Laviolette said. "There was the game to push it to 3-0 where I liked everything we did, including the power play and the penalty kill and the 5-on-5 play, and then there was the game that took place after that, where if you play against a team like Florida that is a high-octane team, we are just feeding them and we can't. We've got to get back to that first part of that game, and you've got to play it consistently for 60 minutes."
NOTES:Verhaeghe's five points are the most in a playoff game in Panthers history. … Panthers forward Mason Marchment missed the game with an undisclosed injury. … Florida has won six games this season in which it trailed by at least three goals, an NHL record. … The Panthers have not won a playoff series since 1996, when they lost to the Colorado Avalanche in the Stanley Cup Final. … Oshie has scored a power-play goal in three straight playoff games, tying the longest streak in Capitals history.