PHOENIX -- A new manager, a frustratingly familiar result for the Arizona Diamondbacks.
"We're starting to build some confidence and playing a lot better baseball," Washington's Ryan Zimmerman said.
Zimmerman hit safely in the 26th consecutive game, the longest active streak in the majors, when he singled in the first inning.
Overall, the Nationals have won four out of five.
"Sooner or later things had to turn around a little bit," Washington manager Manny Acta said. "We had a rough April and May's been good so far, but there's still a ways to go."
Hinch, director of player personnel for Arizona, moved into the manager's job after Bob Melvin was fired Thursday night. The new manager said he liked his team's attitude, despite the loss.
"I was proud of the guys for battling back and kind of answering the bell," Hinch said. "Obviously we left a lot of guys on base, had some opportunities which you always reflect on, but the effort was there. I felt like the intensity was high. We came up a run short, which is unfortunate."
Felipe Lopez had three hits, including a double, and scored twice for the Diamondbacks, who erased most of a three-run deficit but lost for the fifth time in six games.
"It was a tough day," Lopez said, "but everybody was focused on winning a ball game."
Shairon Martis (4-0), coming off a complete game, gave up three runs on nine hits in 5 1/3 innings to get the victory. After struggling the previous night in Los Angeles against the Dodgers, Kip Wells pitched a perfect ninth for his first career save.
Yusmeiro Petit (0-3) gave up four runs on six hits in four innings to take the loss.
Lopez led off the first with a double, advanced to third when Young fouled out, then scored on Justin Upton's ground out. The Nationals took the lead on a two-out, two-run triple by Guzman over Upton's head in right field in the second.
Solo homers by Dunn in the third and Flores in the fourth made it 4-1.
The Diamondbacks cut it to 4-2 when Young -- coming off a 1-for-19 road trip -- tripled in Lopez from first with no outs. But Young was stranded on third when Upton and Mark Reynolds struck out, then Josh Whitesell lined out to right.
Arizona was hitless in 36 tries with runners in scoring position before Josh Wilson singled to put runners at first and the third in the sixth. Pinch hitter Eric Byrnes then snapped an 0-for-17 skid with an RBI single up the middle to cut the lead to 5-3.
Upton extended his career-best hitting streak to 15 games with a single in the seventh, then Whitesell doubled for his first hit -- in 10 at bats -- since being called up from the minors, leaving runners at second and third with one out. Upton scored when Conor Jackson bounced out to third to cut the lead to 5-4.
"I had to show up for work and be professional," Upton said, "and the rest of the team did, too."
Byrnes singled in the eighth, stole second for what would have been the tying run, then was thrown out by Flores trying to steal third.
"He was a little over-aggressive," Hinch said.
Dunn, who spent part of last season with the Diamondbacks, praised Melvin.
"Bob from the time I was here was unbelievable," Dunn said, "a great person, a great guy and a great baseball guy. It's sad that someone like him has to get fired, because I know he did everything in his power. He's just such a great baseball person. I can't say enough good things about that guy."
Petit has allowed eight home runs in 24 2/3 innings this season. ... Washington is 8-8 since opening the season 1-10. ... The Nationals have four saves by three pitchers this season.