Harper had never played a professional game at Yankee Stadium before Tuesday, when he belted his 20th home run of the season in the fourth inning off Masahiro Tanaka in the Nationals' 6-1 loss to the Yankees.
"Didn't really mean anything to the game," Harper said. "Definitely nice to get No. 20, but he threw great out there. Tanaka threw a great game, showed his talent pretty well."
In his next at-bat, Harper led off the seventh inning of a 1-1 game. Down 1-2 in the count, he had an idea -- he squared to bunt.
He fouled Tanaka's pitch back behind home plate and struck out. After the game, Harper stood by his decision.
"You know, it happens. I've done it before, bunted with two strikes before," Harper said. "Not at the big league level, but I've done it before. It was in my head the whole time when I was 1-2. I went with my gut, it didn't work."
As a kid growing up in Las Vegas, 266 miles from the nearest Major League stadium, Harper had his choice of far-flung fandom. He settled on the Yankees because, as he put it, how could you not?
"The pinstripes," he said. "I mean, everything about them. It's the New York Yankees."
He's been here twice before. Each memory is littered with details.
First, he came as a fan, watching Chien-Ming Wang and the Yankees play the Indians in 2005.
"It was raining really hard," he said. "So we had to go down in the tunnel."
A couple of years after that, he returned as a prospect. When Harper was 14, he was part of a pre-Draft showcase at Yankee Stadium, taking batting practice and playing in front of Major League scouts. That time, A.J. Burnett played catch in right field.
"I remember a lot of things like that," Harper said.
Now he's returned as a superstar among baseball's home run leaders. He took the same field he watched Paul O'Neill play on as a kid, facing the team he cheered on from afar.
He's gotten better at hiding his affinity for the club. In October 2011, just over a year removed from being selected No. 1 by the Nationals, he took to Twitter to show that support.
"I love my Nationals, but if I'm going to root for a team in the postseason it's going to be the Yanks!" he tweeted before deleting the post that night. The Nationals weren't in the playoffs that season.
Since then, Harper's been all Nationals, highlighting his Yankee Stadium debut with a home run.
"Definitely happy about it, but it's not good when you lose a ballgame," he said.
Alden Woods is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.