Harper hit the four-bagger Sunday in the Nationals' 6-2 win against the Detroit Tigers at Fitteam Ballpark of the Palm Beaches.
The 2015 National League MVP stepped up to the plate in the third inning to face off against Tigers pitcher Alex Wilson. The right-handed relief pitcher tossed Harper a ball on the first pitch, before catching him looking on a called strike.
Harper laid the lumber on the third offering, sending it over the right field wall and sending an echo of a full-contact crack of the bat throughout the stadium. The long ball also scored Howie Kendrick and gave the Nationals a 3-2 lead.
Harper brought in another run in the fourth inning, smacking a two-RBI single to left center. He is now hitting .300 after four spring training appearances. Harper is 3-for-10 this spring, with four strikeouts, three RBI and a walk.
"Really nice to see that," Nationals manager Dave Martinez told MLB.com, referring to Harper's home run. "Especially with the wind. And also nice to see him go the other way, too, and pick up those RBIs. Matt swung the bat really well. They're getting good at-bats. We just want to see quality at-bats in spring training, and we've seen that over the last few days. I think now the hitters are starting to catch up a bit."
The Nationals face the St. Louis Cardinals at 1:05 p.m. Monday at Roger Dean Stadium in Jupiter, Fla.
Harper hit .319 last season with 29 home runs and 87 RBI. He also made his fifth All-Star appearance. He is under contract for $21.6 million this season and is set to hit free agency in 2019.