MIAMI -- Jose Fernandez stomped off the mound after an arduous second inning cursing and smacking himself on the head with his glove, which sent his sweat flying.
Blame the outburst on a lack of control.
Fernandez (1-1) threw 54 pitches in the first two innings but didn't allow a hit until the fifth and made it through six.
"He's just so emotional," manager Don Mattingly said. "He settles down, and he starts pitching different."
Fernandez improved to 18-1 at Marlins Park, with the lone loss in his previous home start.
His victory was the first this season for a Marlins starter. Miami won at home for the first time this year in six tries.
Washington's Bryce Harper went 0 for 2 with a sacrifice fly. He had homered in his previous four games.
"Every time you get him out, you breathe a sigh of relief," Mattingly said.
Giancarlo Stanton benefited from the new, cozier dimensions at Marlins Park when he homered near the 407-foot sign in center in the fifth. Last year, the ball would have been off the wall.
"It's not like he really cares how far the fence is," Fernandez said. "It doesn't matter to him."
The homer was the third for Stanton, who also singled home a run. He and Fernandez played together for only the 11th time in the past three seasons.
"It's nice to have those guys together and healthy and doing well," Mattingly said.
Tanner Roark (1-2) gave up five runs -- four earned -- and seven hits in six innings. The Nationals have lost two in a row after starting 9-1.
Fernandez improved to 4-0 with a 1.05 ERA in seven starts against the Nationals. He allowed four walks, three hits and one run while striking out nine.
He threw 103 pitches, including 28 to get through a scoreless second inning, when he hit a batter, walked two -- one intentionally -- and threw two wild pitches. He struck out Michael Taylor with the bases loaded to end the inning.
"He was effectively wild," Nationals manager Dusty Baker said. "He got in a couple of jams. We had some opportunities."
Fernandez said the high pitch count had him pounding his head.
"Too many pitches; that's not what you want to do," he said. "I felt very strong. I felt like my body was going 100,000 mph. As the game went on I started catching up my body with my arm, but it shouldn't take me so long to figure it out."
Even so, the Nationals didn't manage a hit until Fernandez's 87th pitch. Taylor doubled with one out in the fifth, took third on a single and scored on Harper's flyout to make it 4-1.
Miami benefited from a replay reversal in the second inning, when an out on a force play at second base was overturned. The runner later scored on Martin Prado's groundout.
Jayson Werth stared at Fernandez after being hit on the left side by a 94 mph fastball.
"Bad timing," Fernandez said. "Last time I faced him, I hit him with a breaking ball. I'm not trying to hit anybody."
Harper retreated and stretched in right field to make a running catch and rob Dee Gordon of an extra-base hit, and made a long run to catch Ozuna's drive on the warning track.
Stephen Strasburg (2-0, 1.98) is scheduled to pitch Tuesday for the Nationals against Adam Conley (0-0, 3.86), who threw six scoreless innings in his most recent outing against the Mets and impressed Mattingly. "He pounded the strike zone," Mattingly said. "He's going to come in there. He's not going to back off. He's going to pitch inside. It's interesting to watch how hitters react to him."
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