With the early 1:35 p.m. ET start time making the outfielders work extra hard to snag fly balls, the sun was a big part of the story.
In the fourth inning, Ryan Braun led off with a high fly ball to center field that Bryce Harper appeared to settle under before losing it in the sun. Braun settled into second with a double, the first of two straight plays in which Harper seemed to struggle with the sun. Aramis Ramirez knocked a fly ball to him in the next at-bat, and Harper had to go to one knee to catch it.
"Just one of those days, I guess," Nationals manager Davey Johnson said. "I was thinking that Harper was having so much trouble, I was thinking about moving [right fielder Jayson] Werth over there. I guess it didn't matter."
Corey Hart added a single to put runners on the corners, and Jonathan Lucroy added a base hit of his own, scoring Braun. Logan Schafer, making the first start of his career, followed with a double to right field, scoring Hart and sending Lucroy to third. Schafer finished 2-for-2 with the double and a single.
In the seventh, Ramirez doubled after Braun reached base on a one-out forceout. After Nats reliever Ryan Mattheus intentionally walked Hart, Lucroy bounced a grounder up the middle. Nats shortstop Ian Desmond dove to corral the ball, but his flip to second baseman Danny Espinosa was wide and Braun scored the go-ahead run.
Milwaukee scored one more in the eighth on a sac fly from Braun that scored Norichika Aoki.
Carlos Gomez, who had pinch-hit in the sixth for Schafer, sent another high fly ball to right field, where Werth quickly lost the ball before turning away and seeing it bounce in front of him. That scored Ramirez and kept the bases loaded for Jean Segura, who grounded out to Desmond to score Hart to make it 5-2.
"I don't think we had any balls that were up in [the sun] like theirs were," Roenicke said. "We knew coming in that that was a possibility with it getting later in the game with the sun. Not that you can do anything about it, sometimes it's just in there and there's not much you can do. It certainly helped us today."
The Nats scored their two runs in the fifth, when Desmond led off with a walk and Espinosa followed with a double to left. Two batters later, pinch-hitter Chad Tracy singled to score Desmond and put Espinosa at third. A sac fly from Werth scored Espinosa for the second run.
The fifth was Gallardo's last inning, as right-hander Brandon Kintzler pitched the sixth and ultimately collected his third win of the season, while Francisco Rodriguez handled the seventh.
Jim Henderson worked a scoreless eighth, and Jose Veras came on in the ninth and recorded two outs before leaving in favor of John Axford with two men on. Axford sealed the win by getting Werth for his 33rd save of the season.
Milwaukee's once-maligned bullpen combined to throw four innings of scoreless, one-hit ball, with four walks.
"It was fun," said Kintzler, who is 3-0 with a 2.61 ERA in 10 1/3 innings since being called up from Triple-A Nashville on Sept. 3. "All of these games are fun to watch from back there, and then all of a sudden you're in the game. It's intense, it's definitely intense. It's fun. It's something I've been thinking about the whole year, thinking I'd be a part of."
Nats starter Chien-Ming Wang, meanwhile, lasted only four innings. The right-handed sinkerballer allowed eight hits but only two runs. Craig Stammen and Zach Duke each pitched an inning for Washington before Mattheus was charged with the three runs in the seventh.