After Evan Gattis homered in the top of the fifth, reminding a sellout crowd at Nationals Park of why he warranted a splendid nickname as a rookie, the home team had a potential inside-the-park home run overturned by an umpires’ review in the bottom of the inning.

So, things were going the Braves’ way again in the first of 19 games between the National League East rivals.

The Nationals tied the score on Ryan Zimmerman’s sacrifice fly in the sixth inning, but Chris Johnson’s sacrifice fly in the eighth lifted the Braves to a 2-1 win in a series opener in which the Braves got another strong pitching performance from an unheralded starter, rookie David Hale.

After David Carpenter struck out three consecutive batters with two runners on base in the eighth inning, Craig Kimbrel struck out two in a perfect ninth inning for his third save in three games.

“They had some opportunities, and we wiggled out of it,” said manager Fredi Gonzalez, whose Braves (3-1) improved to 18-6 in the past 24 matchups with the Nationals, including 9-3 in one-run games.

Hale allowed five hits and two walks in five scoreless innings with four strikeouts, earning no decision but plenty of appreciation from teammates while reducing his career ERA to 0.56 in three starts. The Marietta native was ill Wednesday and Thursday, and Gonzalez didn’t want to push him further.

“It’s good to get that one under my belt,” Hale said. “It’s always fun to throw in front of a crowd like that.”

Nationals starter Jordan Zimmermann recorded nine strikeouts with only one walk in five innings, but one of the four hits he allowed was Gattis’ leadoff homer in the sixth that broke a scoreless tie.

Gattis took a 92-mph fastball for a called strike on the first pitch, and when Zimmermann threw the same thing on the next pitch, “El Oso Blanco” crushed it. It was a no-doubt-about-it homer that sailed out in the same area as Gattis’ homer on a chest-high Stephen Strasburg fastball last year in the catcher’s rookie season.

Controversy arrived in the bottom of the fifth when Ian Desmond led off with a line drive to the left-field corner that looked like a double. When the ball went under a gap in the fence and stayed, left fielder Justin Upton raised his hands to signal it had lodged under the padding. Desmond kept running.

When the umpire didn’t signal the play dead, and with shortstop Andrelton Simmons shouting to throw the ball, Upton went down and retrieved it and threw. But Desmond already was nearing the plate.

“It didn’t look like (third-base umpire Marvin Hudson) was coming out to look at it,” Upton said. “Simmons was panicking, telling me to throw the ball, so I picked it up and threw it. … There was a little bit of confusion, but it got worked out.”

Gonzalez asked for a review under the new replay system. The umpires conferred, the play was reviewed, and the call overturned. Desmond was sent back to second base as a crowd of 42,834 booed lustily.

The umpires said the ball lodged under the padding and awarded Desmond two bases, per Rule 7.05F.

After the Nationals tied the score with a run off rookie Gus Schlosser in the sixth, the Braves regained the lead in the eighth. Jason Heyward drew a leadoff walk against Tyler Clippard (0-1), who struck out B.J. Upton — he was 0-for-4 with three strikeouts — before Freddie Freeman singled. Heyward alertly raced to third, and Johnson’s fly put the Braves ahead.

After Freeman’s leadoff single in the fourth, Zimmermann struck out the next three batters, beginning with Johnson.

“Zimmermann is tough, man,” Johnson said. “Usually anytime we face the Nationals, we know with the arms they’re throwing out there and our pitching staff, we’re going to get into games like this. So it was nice for me to get in that RBI situation and get the sac fly. That’s kind of my job.”

Clippard has given up at least one run in all seven appearances against the Braves since the beginning of last season.

Carpenter allowed a single and walk to start the eighth, then struck out Adam LaRoche, Ryan Zimmerman and Bryce Harper. Jordan Walden gave up a double in the seventh, but Luis Avilan (1-0) induced an inning-ending ground out by Denard Span.

Harper was caught stealing after a one-out single in the second inning, and Desmond was caught in a rundown between second and third when he tried to steal after the homer-turned-double in the fifth. LaRoche was out easily on a strong relay throw to the plate by Simmons after Upton misplayed Zimmerman’s one-out double in the fourth.