ATLANTA -- The Braves insisted they weren't trying to hit Bryce Harper.
They were just going for the knockout punch in the NL East race against the Nationals.
The Braves, who swept a three-game series at Washington on Aug. 5-7, lead the season series 11-3, including six straight wins.
Jason Heyward had two hits and scored one run for Atlanta, which stretched its lead over the second-place Nationals to 15 1/2 games.
"There's a lot of baseball to be played," Upton said. "Our lead is pretty big right now, but crazier things have happened in baseball. You've got to go out and win as many games as you can."
Upton's 23rd homer to left-center came on a 2-2 pitch from Ian Krol (1-1). It was his third career game-winning homer and second of the season.
"It's a great feeling when you can go out and win the ballgame for your team," Upton said. "There's nothing like that."
Scott Downs (2-0) pitched a scoreless 10th for Atlanta.
Harper was hit by pitches in the fourth and eighth innings by Alex Wood and Luis Avilan, respectively. Home plate umpire Marty Foster warned both benches after Avilan hit Harper on his shoulder in the eighth.
Washington's players rose to the top of the dugout but didn't come onto the field.
It wasn't the first time Harper had been hit by a pitch against the Braves this month.
Both Atlanta pitchers insisted they didn't try to hit Harper.
"I tried not to look at him," Wood said of Harper. "It was embarrassing to hit somebody with a curveball."
Avilan was trying to protect a 2-1 lead when he hit Harper.
"I didn't want to put the runner on," Avilan said.
"I was like, I hope he doesn't think I did it on purpose. We're leading 2-1. ... I felt bad because I almost hit him in the head because it's dangerous, you know."
Harper did not talk with reporters after the game.
Nationals manager Davey Johnson said he thought Avilan should have been thrown out of the game.
Asked if he thought Braves pitchers were trying to hit Harper, Johnson said, "I hope not, because it's ridiculous. In a close ballgame, they've got a lot more to lose than we do at this point, so it would be a ridiculous thing to do.
"After he got hit the second time they should have thrown [Avilan] out of the ballgame and be done with it. But it's their choice."
On Aug. 6, both benches emptied when Harper was hit by Julio Teheran in the Braves' 2-1 win at Washington.
Downs threw an inside pitch past Harper to the backstop before walking Harper with one out in the 10th. Jayson Werth hit into a double play to end the inning.
Wood gave up one run and five hits and no walks and a career-high nine strikeouts in 6 1-3 innings.
Washington's Taylor Jordan did not allow an earned run, but was hurt by three errors. Jordan allowed two runs, both unearned, and seven hits and three walks in six innings.
Heyward led off the first inning with a single and took off for second base on ball four to Upton.
After Janish advanced to third on Heyward's single, shortstop Ian Desmond fielded Upton's grounder and threw to second to force Heyward. Second baseman Anthony Rendon attempted to complete the double play, but threw wild to first for an error, allowing Janish to score for a 2-0 lead.
There was no reaction from Harper when he was hit by a pitch from Wood to lead off the fourth.
Harper calmly jogged to first base and then made a comment to Freeman at the bag, prompting both to laugh. Harper advanced to third on Werth's single and scored when Desmond hit into a double play.
Harper wasn't laughing after he was hit by Avilan's pitch in the eighth following a double by Ryan Zimmerman. Luis Ayala replaced Avilan and gave up a single to Werth as the Nationals pulled even at 2-2.
Upton also hit a game-winning homer against the Cubs on April 6. ... RHP Drew Storen, recalled from Triple-A Syracuse on Thursday, pitched a scoreless ninth. ... Braves 2B Phil Gosselin, recalled from Triple-A Gwinnett, made his major league debut as a defensive replacement in the 10th. ... Braves RHP Jordan Walden, who hadn't pitched since taking a liner off his pitching hand on Saturday, said his hand is fully recovered. ... The series continues Saturday night when Atlanta's Mike Minor will try for his 13th win against Washington's Stephen Strasburg, who is only 6-9 despite a 2.83 ERA.