Braves pitchers have throttled Washington hitters for nearly a calendar year now, an impressive run that continued unabated Friday when rising rookie Alex Wood faced the Nationals for the first time.

But after the left-hander allowed only five hits and one run with a career-high nine strikeouts in 6 1/3 innings, things got real interesting in the series opener at Turner Field, where Bryce Harper was hit twice more by Atlanta pitchers and Justin Upton’s one-out solo homer in the 10th inning gave the surging Braves a 3-2 win.

“When you can go out and win the ballgame for your team, there’s nothing better than that,” Upton said after his second walk-off homer this season gave the Braves their 18th win in 20 games.

He punished a 2-2 hanging curveball from left-hander Ian Krol, Upton’s third homer in four games against the Nationals over the past 12 days. The Braves improved to 11-3 against the second-place Nationals and pushed their commanding lead back to 15-1/2 games over the defending NL East champions.

“Our lead is pretty big right now, but crazier things have happened in baseball,” Upton said. “So you have to go out and win as many ballgames as possible. You don’t give any of them away.”

Crazy things happened Friday, when Braves reliever Luis Avilan hit Harper in the back with a fastball with two outs and a runner on second in the eighth inning. It was the second time the brash young Nationals slugger was hit Friday, after also being hit Aug. 6 in Washington during the Braves’ three-game sweep.

“You’re not going to hit Harper there (on purpose), the winning run, lefty on lefty with two outs,” Braves manager Fredi Gonzalez said. “That’s ridiculous. I know he’s upset with it and I don’t blame him. Nobody likes to get hit but for it to be intentional — it’s not even close.”

Harper declined to comment after Friday’s game.

When he got hit at Nationals Park it caused a benches- and bullpens-clearing incident, along with some words exchanged between Harper and pitcher Julio Teheran, although no physical contact between any opposing players.

The benches didn’t clear either time he was hit Friday, and Harper didn’t do anything more than go to first base after being hit in the right shoulder by a breaking pitch from Wood in the fourth inning or Avilan’s 91-mph fastball, which got him high on the left shoulder after Harper spun around.

Gonzalez knew how it probably looked to some people.

“It looked awful but it’s not (intentional),” he said. “Really, those situations are not one to hit people on purpose or any of that kind of stuff.”

Avilan already had given up a two-out double to Ryan Zimmerman in the eighth and was replaced after hitting Harper. Gonzalez then brought in reliever Luis Ayala, who gave up an RBI single to Jayson Werth that made the score 2-2 and snapped Avilan’s string of 35 consecutive appearances over nearly three months without an earned run.

“The people who think I did it on purpose don’t know anything about baseball,” Avilan said. “I don’t think he thought I hit him on purpose, because of the situation. We were winning 2-1, I didn’t want to put the lead run at first. If I’m going to do it on purpose, I’m not going to (throw it there). I almost hit him in his head.”

Home-plate umpire Marty Foster warned both benches after the second incident. Harper gathered himself and after bending over to let the sting subside and catch his breath, went to first base. Gonzalez replaced Avilan, who got a loud ovation from a crowd of 35,663 when he came off the field.

“I wasn’t good today,” Avilan said. “It was probably because the ball moved side-to-side. I feel bad for (Harper) because I don’t want to hit him, especially in that part of his body, near his head. Just a bad day for me.”

In both situations, the circumstances made it unlikely that either pitch was thrown intentionally at Harper. Nationals manager Davey Johnson was asked if he thought the Braves threw at Harper either time Friday.

“I hope not, cause it’s ridiculous in a close ballgame,” Johnson said. “And they’ve got a lot more to lose than we do at this point. So it would be a ridiculous thing to be doing…. After he got hit the second time, (the umpire) should’ve thrown (Avilan) out of the ballgame.”

After Wood hit Harper with a curveball to start the fourth, Werth singled, and Harper scored when Ian Desmond grounded into a double play, cutting the Braves’ lead to 2-1.

“It was a knuckle-curve,” Wood said of the pitch that hit Harper. “You never want to let the leadoff hitter get on. It just kind of came out of my hand a little early. The crowd started cheering, but it’s like, it’s a breaking ball I hit him with. It’s a complete accident.”

The Braves jumped to a 2-0 lead in the first three innings against Nationals rookie Taylor Jordan, making his ninth start. Jason Heyward led off the first with a single and went to third base on an errant throw by the catcher on an Upton walk. Heyward scored when Freddie Freeman grounded into a double play.

Paul Janish hit a leadoff single in the Braves’ third inning and Heyward singled with one out. With runners on first and second, Upton grounded into a potential double play, but the throw to first was wide, allowing Upton to reach base and run to score for 2-0 lead. Neither of the Braves’ first two runs were earned.

The Braves are 15-3 with a 1.64 ERA in their past 18 games against the Nationals.

“They’ve played pretty good from start to finish and we haven’t,” Werth said. “That’s really the story of the season so far.”

In holding the Nationals to three runs or fewer in 13 consecutive games, the Braves are only the second major league team in 20 seasons to do that to one opponent in that many games in a row. Both times it was done by Braves pitchers, who previously accomplished the feat against the Mets in 2010.

Wood worked out of trouble in the third, fourth and fifth innings and was in position to get his third win in his past four starts before things went sideways on Avilan in the eighth. In the fifth, the Nationals got back-t0-back singles by Wilson Ramos and Anthony Rendon to start the inning, and a Jordan sacrifice bunt advanced both runners.

Wood then struck out Denard Span and Ryan Zimmerman grounded out to end the inning.

“I think that fifth inning was the big one, when I got second and third with one out with the top of the order coming back up,” Wood said. “Those are the innings that make or break you, in terms of having good numbers and being able have success anywhere, to minimize (damage) and be able to get out situations.

“That was probably what I was most proud of tonight, to be able to get out of that inning unscathed. That was definitely pretty big for my confidence, and for the game in general.”

Wood, who has given up one or no runs in each of his past three starts, allowing nine hits and three walks with 19 strikeouts in 18-1/3 innings over that stretch.

“That delivery … was pretty funky,” Werth said. “That’s a guy you need to see a few times to figure out. He pitched pretty good.”

Wood has a 2.76 ERA in six major league starts, including a 1.78 ERA in his past four. Just 14 months removed from pitching for the University of Georgia, he has made quick strides in the big leagues.

“He really has been terrific,” Gonzalez said. “If you didn’t know that he was pitching in college, attending class this time last year, you would have thought this guy’s been around for three or four years.”