WASHINGTON -- The D-backs were not surprised from what they saw from Nationals rookie phenom Stephen Strasburg on Sunday afternoon.

That said, they could not find a way to hang a loss on the right-hander as they dropped a 5-3 decision at Nationals Park.

In losing two of three to Washington, the D-backs dropped their first series since the end of July and finished their seven-game road trip with a 4-3 mark. Not bad for a team that was 15-37 on the road prior to this trip.

"I'd like to be 7-0, but I guess it's an improvement," interim manager Kirk Gibson said. "We have been terrible on the road. We're playing better, no complaints about that. It's always frustrating when you lose, but it's part of the game."

It was the kind of loss that leaves a manager pulling out his hair, as the D-backs missed piling on Strasburg when they had a chance, and then watched their bullpen give it up in the later innings.

Strasburg, who was making his 11th Major League start, fanned two of the three batters he faced in the first inning, but the D-backs were able to get to him in the second.

Adam LaRoche led off the frame with a home run to right on a 2-0 pitch.

"I don't think we saw his best stuff," LaRoche said. "I think he was a little erratic at times. Any time you can throw 99 [mph] and back it up with two offspeed pitches that you can throw at any time for strikes, that makes it tough on the hitters. If he stays healthy, he's got obviously the potential to be around for a long time."

One out later, Mark Reynolds singled and Stephen Drew hit a dribbler to the first-base side of the mound. Strasburg fielded it and threw over Adam Dunn's head at first, allowing Reynolds to score and Drew to go to third.

Gerardo Parra followed with a sacrifice fly, and the D-backs led, 3-0.

"He's got great stuff, great velocity, very good changeup and his breaking ball is very sharp," Gibson said of Strasburg. "We were fortunate. LaRoche has been red-hot and he hit that ball out. He got a little rattled that one inning, but he recovered nicely."

And the D-backs' offense disappeared for the next seven innings.

Strasburg gave up a pair of hits in the fourth, but he was able to fan Parra to end the inning. And after Chris Young singled and stole second with one out in the fifth, Strasburg struck out Kelly Johnson and got Justin Upton to ground out.

"It was exactly what I expected," Johnson said of Strasburg. "Fluid delivery, nothing deceiving there, but the ball jumps out of his hand and he's not afraid to come in. He doesn't have to be perfect. I wasn't expecting the changeup to fool me as much, but like I said, he set me up personally really well."

The less-heralded starting pitcher in the game, Barry Enright, was not able to make the lead hold up.

The right-hander allowed a run in the second on an RBI single to center by Ivan Rodriguez, and then after Ryan Zimmerman led off the fourth with a single, Enright hung a breaking pitch to Josh Willingham, who deposited it over the wall in left to tie the game.

Strasburg departed after the fifth having allowed five hits while fanning seven.

"I thought I made a lot of improvements," Strasburg said. "I started to get the feeling back. I was able to locate my pitches a lot better today. It was a good win. It was good to go out there after a tough day yesterday and win the series."

While Tyler Clippard, Sean Burnett and Drew Storen were able to hold the D-backs scoreless for the final four frames, the Arizona bullpen was not able to do the same.

Lefty Jordan Norberto (0-2) allowed a two-out opposite-field single to Ian Desmond in the seventh that scored Adam Kennedy with the go-ahead run.

One inning later, Zimmerman gave the Nats some insurance when he led off with a homer off Esmerling Vasquez.