After splitting games on the road in Washington and coming back to Pittsburgh tied 1-1 in the series, the Penguins were looking to take a lead.
The Penguins would jump out to a 2-0 lead in the first period with goals from Patric Hornqvist and Tom Kuhnhackl a minute apart.
A second period goal from Carl Hagelin extended the lead to 3-0.
It was at this point the Capitals started bringing the heat and the Penguins had to hang on for dear life.
Alex Ovechkin would get the Caps on the board before Justin Williams pulled them within one goal late in the third period.
The Penguins hung on with Matt Murray making 47 saves on 49 shots and got the edge in the series that they needed.
Kris Letang would find himself in trouble with a headshot on Marcus Johansson that earned him a 1-game suspension.