RALEIGH, N.C. — The Islanders, so nearly, returned to New York with home-ice advantage and momentum in the series.

Instead, they will get on a plane back to Long Island searching for answers after a gut-punch 4-3 overtime loss featuring a blown third-period lead, a pair of uncharacteristic goals let in by Ilya Sorokin and the game-winner coming from Jesper Fast.

The first playoff game at UBS Arena on Friday night is now an absolute must-win for the Islanders, who need to find an answer for Carolina’s speed advantage and ensure that this loss is not the backbreaker to their season.

It looked as though the Islanders would leave PNC Arena with a win after Brock Nelson gave them their first lead of the series 9:18 into the third period, burying a wrist shot off the rush.

But the lead did not last long.

Just 4:01 later, Jaccob Slavin tied the game up for Carolina, beating Ilya Sorokin on a tight-angle wrist shot that banked off Sorokin’s back and in.

The Islanders did enough to get the game to overtime, killing off Ryan Pulock’s tripping penalty late in regulation.

But in the extra period, Fast set the building alight with the winning goal.