After going down 2-0 early, New York scored four straight goals with four different players, including three in the third period. Josh Bailey's short-handed goal about seven minutes into the third put the Islanders ahead and they never looked back.
The Islanders have been impressive so far in Toronto, defeating the Florida Panthers in four games during the qualifying round. Head coach Barry Trotz now has a chance to defeat his former team after the solid start from the No. 7 seed in the Eastern Conference.
Washington, the No. 3 seed, struggled during the round robin and now have to come from behind to avoid a second straight first-round exit.
Braden Holtby, G, WAS: 27 saves, 4 goals allowed
T.J. Oshie, C, WAS: 2 goals
John Carlson, D, WAS: 2 assists
Semyon Varlamov, G, NYI: 26 saves, 2 goals allowed
Josh Bailey, C, NYI: 1 goal, 1 assist
Mathew Barzal, C, NYI: 2 assists
Islanders Get Physical to Open Series
The Islanders showed what kind of series this was going to be early on with a physical approach.
The first period featured plenty of penalties and an intensity that showed these teams weren't easing into the game:
New York ended up with 10 penalties for a combined 23 minutes while Washington had 17 penalty minutes.
Captain Anders Lee also played a big role in this with his actions in the first period:
There were no goals in the first period but the tone it was seemingly as important as the rest of the game as it set the tone. It also helped the Islanders stay motivated even after facing an early deficit.
The Capitals scored the first two goals before Jordan Eberle got on the board for New York:
In the third period, Lee, Bailey and Anthony Beauvillier scored to put the Islanders in front:
New York eventually held on to seal the come-from-behind win.
It showed impressive resolve against an experienced and proven team. Not only did this lead to a win, it showed the squad is up to the task of competing in this series.
T.J. Oshie Remains Huge X-Factor for Capitals
If the Capitals are going to make a run in the playoffs, they need more than just Alex Ovechkin scoring goals.
Oshie had eight goals, including six on the power play, during the Stanley Cup run two years ago. He had just one goal in four games as the team was eliminated in the first round last season.
The 33-year-old is already a bigger factor this year with two goals in Game 1, both coming on the power play in the second period:
He showed his nose for the goal, which is vital for Washington taking advantage on special teams.
Oshie also showed his value beyond scoring later in the period, preventing an Islanders goal with a heady play in his own net.
His production is even more important if Nicklas Backstrom is forced to miss more time after coming out of Wednesday's game with an injury. The center took a hard hit from Anders Lee in the first and was unable to return. Lars Eller is also out with an injury.
Washington at least got John Carlson back from his injury just in time for him to earn two assists, but the team still needs more players to put it in the net.
This is especially true if Braden Holtby continues to struggle in goal for Washington:
The pending free agent won't help his value with a rough postseason.
The two teams will be back in action for Game 2 on Friday at 8 p.m. ET as the Capitals try to even the series.