Harper made a tumbling barehanded catch in centerfield and then led off the ninth inning with a double to set the stage for Ian Desmond's two-out game-ending home run that gave the Nationals a 5-4 victory over the visiting Arizona Diamondbacks on Wednesday night.
"He was born for these situations," Washington manager Davey Johnson said of Harper.
In the sixth inning, Harper fell down in the right-center gap while attempting to catch a fly ball off Jason Kubel's bat. As he landed in the grass, Harper secured the ball in his ungloved right hand.
"I was wondering if anybody saw that," Harper said. "It went underneath my glove, and I caught it with my bare hand on the back side of it."
Harper, the No. 1 overall pick in the 2010 draft, also had his first multi-hit game with two doubles and a single from the No. 7 spot in the lineup. He scored his first career run in the fourth inning, knocking the ball out of the catcher's glove.
The Nationals snapped their own five-game losing streak and ended the three-game winning streak of the Diamondbacks.
"We needed it," Johnson said. "No doubt about it."
Henry Rodriguez (1-1) struck out two in the top of the ninth to earn the win. J.J. Putz (0-2) blew the save and took the loss. After Harper's leadoff double, Putz struck out the next two batters before Desmond's homer to left.
"It won't be the last time it happens to us this year," Diamondbacks manager Kirk Gibson said. "We're playing good baseball. We just have to shake this one off and come back tomorrow."
Harper nearly homered in the fourth inning, settling for an RBI double off the top of the wall. The next batter hit a grounder to Arizona second baseman Aaron Hill, who misplayed the ball. Although the ball didn't go far and he started the play at second base, Harper attempted to score.
Hill's throw beat Harper to the plate, but a sliding Harper knocked the ball from catcher Miguel Montero's glove to score his first major-league run.
"I was trying to make something happen at the plate, go in hard and try to make something happen," Harper said.
Harper singled in the second inning for his first hit at Nationals Park. Harper hit a weak grounder to the right side of the infield. Saunders raced off the mound and dove, his glove flying off his hand at the ball, and remained sprawled on the field for a few moments as Harper reached safely.
After being examined and tossing a couple of warmup pitches, Saunders remained in the game and threw to first to start a rundown that ended the inning with Harper caught stealing.
Harper also showed off his arm, holding Kubel at third base on a fourth inning flyout by throwing a bullet to the catcher. The next hitter flew out to left fielder Xavier Nady, not much deeper than Harper was, and Kubel scored.
Even Harper's seventh-inning flyout to centerfield, just short of the warning track, drew gasps.
"He's got a lot of energy," Desmond said. "He brings a lot of energy to the team, and that may have been what we needed."
Jayson Werth singled in the eighth inning after Upton dropped a foul ball, keeping Werth at the plate. That put two runners on base, but Craig Breslow entered the game and retired the next three batters, the final two by strikeout. That also delayed Harper's fourth plate appearance to the ninth inning.
When Desmond came up in the ninth, he followed the advice he previously gave Harper and Stephen Lombardozzi.
"Frank Robinson told me that you've got to watch the pitcher, you've got to watch the pitcher, you've got to watch the pitcher," Desmond said.
Desmond saw Putz was elevating his fastball and splitter high, and locked in on those pitches. The win comes after a stretch where the Nationals' struggles at the plate drew plenty of attention.
"You guys are asking the wrong questions," Desmond said. "We're in first place. We're playing good baseball."
Nationals third baseman Ryan Zimmerman, who's on the disabled list with an inflamed right shoulder, could return Tuesday at Pittsburgh, according to Johnson. That will depend on a Friday hitting session, but not a rehab assignment. "I'll take him cold turkey," Johnson said. ... Chien-Ming Wang, who's recovering from a left hamstring strain, will throw two more rehab stints of about 75 pitches each before a decision is made on his next step, Johnson said. Johnson said he hadn't decided whether Wang will start or relieve upon his return. ... Washington pitcher Stephen Strasburg won National League Pitcher of the Month for April, becoming the first National to claim honor besides Chad Cordero, who won in June 2005. Strasburg went 2-0 in five starts with a 1.13 earned-run average, a league-best 34 strikeouts and six walks. ... Stephen Drew (ankle) will play three innings Thursday in a rehab assignment, Arizona manager Kirk Gibson said. ... Diamondbacks pitcher Wade Miley won National League Rookie of the Month for April. He won both his starts and one of his three relief appearances, notching a 1.29 earned-run average and striking out 15 in 21 innings. "It's nice, but at the same time, I told him to keep the same hat size," Gibson said.