D-backs starter Wade Miley pitched his way into and out of trouble for six innings for his first Major League win in just his second big league start since being promoted from Triple-A Reno.
Miley allowed five hits and walked four, as the Nats stranded nine runners in his six shutout innings.
"I kept getting into some pickles and just kept trusting Miggy and worked through it," he said. "The defense made plays behind me and got me out of the jams we were in."
Chris Young gave Miley some breathing room in the sixth when he smacked a two-run homer off John Lannan (8-10).
Miley's outing was quite a contrast from his debut against the Braves last weekend, when he allowed five runs on seven hits in just four innings.
"He stayed under control, he made good pitches when he needed to," Montero said. "He was able to throw the fastball in for a strike and a ball, he was able to keep them off-balance with the changeup. To be honest, I saw him in Atlanta and I thought he was going to be a big help for us. I think he's going to be a good pitcher."
Though he would have preferred not to have found himself in so many jams, Miley did take something positive from it.
"Absolutely, just being able to trust the catcher, we're on the same page and make a pitch knowing you've got eight guys, seven guys behind you to make plays and do everything they can," Miley said.
Said Nationals left fielder Jonny Gomes: "It's always a tough time with the younger guys. There's not many reports on him, not many at-bats. Maybe by the time you think you have him figured out he's out of the game. We got some runners on, but he beared down and started pitching a little different with runners in scoring position. He did a good job."
The Nats closed to within 2-1 in the seventh against reliever Bryan Shaw, but the D-backs' offense, which had struggled this entire trip, finally busted out.
Arizona scored three in the eighth, two on Paul Goldschmidt's homer off All-Star reliever Tyler Clippard.
Goldschmidt came into the game mired in an 0-for-14 slump and D-backs manager Kirk Gibson had given him two straight days off in hopes it would help him.
"It was nice for the team," Goldschmidt said when asked if he was pleased with his 3-for-4 night. "Even though we'd won the past couple games the bats hadn't come around and it was a 2-1 game, we were able to get those three runs and tack on another three, so it was definitely a good confidence builder."
The D-backs added three more runs in the ninth to put the game out of reach.
Arizona left on the trip with a 3 1/2-game lead on the Giants in the National League West, and the D-backs now own a three-game advantage with 31 left to play.
The D-backs won the first game of the trip in Philadelphia before dropping the final two of that series and all three in Atlanta before losing the first game against the Nationals.
"We had a tough schedule and ran into some hot teams, and didn't play very well against them," Gibson said. "We'll have to play much better. Obviously, you have to have better offense, have to score some runs, we'll give them some credit. We learned some lessons. We'll be better prepared. But to come away with three out of four here was big. It was a great finish to a very long trip."