Max Scherzer threw seven scoreless on the mound in Marlins Park and handed the one-run lead Ryan Zimmerman gave the Nationals with his second-inning home run to the Nats' eighth and ninth inning options, Drew Storen and Jonathan Papelbon.
Storen threw a quick, 10-pitch, 1-2-3 eighth and Papelbon earned his 18th save in 18 opportunities this season with a nine-pitch, 1-2-3 ninth.
"We didn't have many opportunities today," Matt Williams told reporters after the win.
"But we got one on [Ryan Zimmerman's] swing and it turned out to be enough. Sometimes those are the games you're going to have to win.
"Other days you're going to swing it like we did yesterday. But regardless, we'll take the W."
Scherzer bounced back from a rough-ish five-inning start against the Pittsburgh Pirates in which he gave up seven hits and five runs, with a solid, 109-pitch start against the Marlins in which he gave up three hits and three walks but no runs.
"I don't know if there was anything different," Williams said when asked about the difference between Scherzer's last two starts.
"He was aggressive. Fastball command was pretty good today both in and out, up when he needed it."
"It was unbelievable," Nationals' catcher Wilson Ramos said after working with Scherzer all day.
"Everybody saw the game today. It was a really good game. 1-0 score. Seven scoreless for him. He was aggressive all game. Very good. He was aggressive all game like his normal approach every game. I know in the last start he struggled a little bit, but today totally different. He was aggressive and he did his job really well."
Papelbon's debut as a National, after the trade that brought him over from the Phillies, was a brief one, but he stayed perfect in save opportunities this season.
"He's not afraid to throw his fastball," Williams said.
"He throws it in the strike zone, locates it and uses his other pitches. He got [Michael Morse] on a curveball and he was ready to go for the ninth.
"He was ready last night in case we needed him and he was ready again today, so we're glad to have him."
The combination of Storen and Papelbon, Ramos said, was impressive.
"That's good for the team," Ramos told reporters. "Like I told my teammate [Jose] Lobaton, I told him two minutes ago, if those guys come in like that every single game, it's hard for us to lose games. They came in today, really, really good, really aggressive, attacked the hitters really well and that's what we need. We need those [guys] like that at the end of the game. Amazing job for them."
Papelbon, in particular, Ramos said, was really sharp in their first inning working together.
"Aggressive guy. Smart guy. Pitches work good. Got really good. Stuff. That's the first time. I'll have more time to see different situations, but for now it was really good."
• We talked about the Nationals' new late-inning set-up, Ryan Zimmerman's blast and the Nats' decisions with the trade deadline tomorrow on the latest edition of Nats Nightly: