Batting sixth in the lineup and playing left field for the first time since turning pro, MLB.com's No. 3 preseason prospect, went 2-for-3 with a walk and a run scored as the Harrisburg Senators defeated the Erie SeaWolves, 8-1.
"I'm going to go out, play hard and let [the Nationals] make the decisions [on where I play]," Harper told the Harrisburg Patriot-News. "I'm just trying to win ballgames here in Harrisburg...It's one step closer to the big leagues."
Harper, who skipped Class A Advanced when he was promoted to Harrisburg on Monday, hit a two-out single to center field on the first pitch he saw in the first inning, advanced to third base on following Archie Gilbert's double to left field and scored on Stephen King's two-RBI double to center.
After popping out to third baseman Francisco Martinez in foul territory in the third, the top overall pick of the 2010 Draft went the other way with a single to left field to lead off the fifth . He went from first to third on Gilbert's groundout, but was stranded when the final two batters struck out to end the inning.
Tyler Stohr walked Harper on four consecutive pitches in the seventh, but the Southern Nevada product was retired at second base when Gilbert rolled over a pitch to shortstop Gustavo Nunez.
The 8,092 people on hand to witness the 18-year-old's Eastern League debut was the largest crowd in club history, breaking the 8,078 mark set at last year's All-Star Game.
In 72 games with the Class A Hagerstown Suns of the South Atlantic League, Harper hit .318 with 14 homers, 46 RBIs and 19 stolen bases. Named to the Sally League midseason All-Star team, Harper -- who hit third in every game except one and did not play an inning in left field during his three-month spell with the Suns -- also scored 49 runs and drew 44 walks. His .423 on-base percentage led the league.
Nationals general manager Mike Rizzo told MLB.com on Monday: "After going through a few nagging injuries, he showed me that he had enough at-bats at [the Class A level] and succeeded at that level. We figured we would challenge him to the next level in the Minor Leagues and see if he could handle Double-A pitching up there, with a good league and a bunch of prospects."
On Sunday, Harper will represent the U.S. squad when he faces off against baseball's top prospects in the 2011 XM Futures Game in Phoenix, Ariz. The Nationals expect Harper to remain in Harrisburg for the second half of the season before playing every day in the Arizona Fall League this offseason.
On Monday, catcher Derek Norris went 3-for-4 with two homers, three RBIs, three runs scored and a walk and Bill Rhinehart added two longballs, three RBIs and a pair of walks.
Harrisburg's Brad Peacock (10-2) allowed one run on five hits while walking two and striking out nine over six innings to become the Minors' first 10-game winner of the year. He lowered his ERA to 2.10, which ranks second only to Richmond's Eric Surkamp (1.72), and he extended his league-leading strikeout total to 129.