Nicklas Backstrom scored 11:09 into overtime to lift the Washington Capitals to a 2-1 victory on Tuesday night, and even their first-round playoff series against the New York Islanders.
Alex Ovechkin also scored and assisted on the decisive goal, which came off a faceoff to the right of the Islanders net. Backstrom dug the puck out in the right corner and worked his way up the boards.
He snapped a shot near the blue line that went through a crowd and sneaked inside the far post.
Casey Cizikas scored for the Islanders as the series shifts to Washington for Game 5 on Thursday.
It was the second consecutive game decided in overtime, after John Tavares needed 15 seconds to seal the Islanders' 2-1 win on Sunday.
The Capitals had two of the best scoring chances to open overtime, and both set up by Marcus Johansson.
Five minutes in, he circled the Islanders net and sent a pass through the middle to Evgeny Kuznetsov, who was stopped by Jaroslav Halak.
Three minutes later, with the Isles caught on a line change, Johansson got the puck at the New York blue line and passed to Jason Chimera breaking in alone. Halak kicked out his right pad to make the save. Halak finished with 28 saves.
Ovechkin opened the scoring at 13:06 of the first off a faceoff to the left of the Islanders net. Backstrom won the draw and got the puck back to John Carlson at the right point. Carlson blasted a shot which Ovechkin deflected in while cutting across the middle.
It was Ovechkin's second goal of the series and only second in 13 road playoff games dating to Game 2 of Washington's second-round series against the New York Rangers on April 30, 2012.
Cizikas tied it with 13 seconds left in the opening period.
Cal Clutterbuck sparked the play by driving through the middle and getting off a bouncing shot. Braden Holtby stopped the shot, but couldn't control the rebound which Cizikas flipped in while driving to the left post.
The third period featured both teams trading chances.
Cizikas nearly scored four minutes in when he deflected Calvin de Haan's point shot, only to have it stopped by Holtby. Holtby had 36 saves.
Halak was sharp during a Capitals power play that began 6:40 into the period. First he stopped Carlson's hard shot from the blue line, and then foiled Ovechkin attempting to convert the rebound.
Later, Halak was late getting across to his left, but reached back just in time to stop Marcus Johansson, who was set up in front by Ovechkin.
The Islanders then nearly scored a short-handed goal, when Clutterbuck had his shot go off the crossbar during a two-on-one break.
It was a tightly played game throughout.
The Capitals had stretches of controlling the puck in the Islanders zone, and New York countered with its speedy transition game.
Ovechkin had a golden opportunity to score his second goal late in the second period, when Backstrom set him up for a one-timer above the left circle. Ovechkin didn't get all of it, and the shot fluttered to Halak, leaving the Capitals star looking to the rafters in frustration.
Seconds later, the Islanders pounced on the transition. Brock Nelson sped up the right boards and flipped a centering pass to Josh Bailey, who got off a good shot. Holtby made the stop by getting his right pad down just in time.
Islanders veteran defenseman Lubomir Visnovsky did not return after being bowled over by hard-charging Capitals forward Tom Wilson in New York's right corner. Visnovsky was slow to get up and held a towel to his nose while skating off to the locker room.
Wilson was penalized for charging.
Capitals defenseman Brooks Orpik had a scary moment when he was cut across the right side of his face by Carlson's skate blade with a minute left in the first period. Orpik immediately dropped his gloves and skated toward the gate leading to the Capitals' locker room.
He returned for the start of the second period.
Orpik was falling forward over Carlson during a scramble in front, when the toe of Carlson's skate caught Orpik just to the right of his mouth.
The "Let's Go Islanders!" chants started 40 minutes before game time, with a large group of jersey-wearing fans gathered near the team's on-ice gate.
The Islanders are guaranteed playing at least one more game at Nassau Veterans Memorial Coliseum. The franchise is leaving its 43-year-old home and moving to Brooklyn next season.
After distributing orange-colored towels that read, "Let's Make History. One More Time," on Sunday, the Islanders distributed blue-colored ones on Tuesday.
NOTES: Capitals coach Barry Trotz made two changes to his lineup. Rookie LW Andre Burakovsky made his playoff debut and C Michael Latta returned after sitting out the past two games. Curtis Glencross sat and Eric Fehr is to miss at least two games after sustaining an upper-body injury in Game 3. ... The Islanders have not advanced past the first round in their previous six playoff appearances. They last did it with a 4-2 series win against the Capitals in 1993. ... The Capitals scored the opening goal for the first time this series.