By Erik Boland

Newsday

WASHINGTON — Bryce Harper gave the hometown crowd exactly what it wanted.

But he made the 43,698 crammed into Nationals Park sweat it out.

The Nationals outfielder, serenaded by loud “Let’s go Harper! Let’s go Harper!” chants throughout the night, rallied in the final round to win the Home Run Derby on Monday night in his home ballpark.

Harper, the No. 2 seed in the competition and with his father throwing to him, beat the Cubs’ Kyle Schwarber, the fifth seed, 19-18, in the final round.

“I’m only as good as my BP guy and this crowd,” Harper said afterward in a televised interview heard inside the stadium, the fans still cheering. “Wow!”

Schwarber, who beat the Astros’ Alex Bregman in the first round and the Phillies’ Rhys Hoskins in the semifinals, went first in the championship round and put up an impressive number.

With the crowd roaring, Harper, swinging his special cherry blossom bat — with the stars and stripes adorning — and wearing a red and white-striped bandanna and a sleeve on his right arm, also with the stars and stripes, got off to a slow start.

With 1 minute and 20 seconds left in his four-minute block, Harper trailed 18-9.

“I better figure it out or I’m going to lose,” he said of his mindset.

Harper did, hammering 10 balls out to tie it. In his 30 seconds of extra time — earned because he hit at least one ball at least 440 feet — Harper won it on his second swing.

Speaking earlier in the day Harper, who finished runner-up to Yoenis Cespedes, then of the A’s, the last time he competed in the event in 2013 at Citi Field, said this “probably” would be the last time he participated and that he wouldn’t have Monday had it not been at Nationals Park.

He more than understood why Aaron Judge, who put on an electric show in winning last year in Miami, decided back in the spring he wouldn’t try to defend.

“It’s so tiring,” Harper said. “I don’t think people understand that. Your forearms hurt, your back hurts, your obliques hurt, everything. It’s a long time to keep swinging and swinging and swinging. It’s a different animal.”