PHOENIX -- The Washington Nationals hope their latest big win -- this over one of the National League's top starting pitchers -- doesn't somehow turn into a major loss.

Brian Goodwin homered to start a four-run first inning, and the Nationals overcame the early departure of star right-hander Stephen Strasburg to beat the Arizona Diamondbacks 6-2 on Sunday.

Wilmer Difo also homered for Washington, and the National League East-leading Nationals coaxed seven innings out of five relievers in their often unreliable bullpen to win for the three-game series and the eighth time in 10 games overall.

The anticipated pitching duel between All-Star pitchers Strasburg and Robbie Ray never developed. Washington roughed up Ray for five runs in the first three innings, and Strasburg was pulled after two innings with what manager Dusty Baker said afterward was arm tightness.

"We think he's good, and we took him out for precaution," Baker said. "He's had a little stiffness and he couldn't get loose, even though he's throwing the ball well. We'll analyze it when we get back home and hopefully we'll have an answer on Tuesday."

Strasburg, who has a lengthy injury history, already thinks he knows the answer.

"I think it's something I can work through," said Strasburg, who said the discomfort is more in his forearm than his previously repaired elbow. "Let's address it and clear it out.

"I just want to be there in the end (of the season). If coming out after a couple of innings today puts me in a better position to do that, I'll take it."

Washington may be cruising in its division with a 12-game lead, but losing Strasburg for any length of time would further stretch an already thin pitching staff that recently was forced to bring in the heavily traveled Edwin Jackson to be the No. 5 starter.

"It's not intense pain, it's just general (things) and kind of tough getting loose," Strasburg said. "The All-Star break kind of messed it up for me throwing-wise and treatment-wise. It's taking me a while to get back into the swing of things."

With Ray (9-5) making an uncharacteristically poor start -- he had been 7-1 in his previous 10 starts -- the Diamondbacks failed again to get any post-All-Star-break traction as they dropped their 11th in 15 games.

"Offensively, they came out and caught us with a quick punch and staggered us," Arizona manager Torey Lovullo said. "The four (first-inning) runs were obviously some very well-hit balls and mistakes over the plate. We got sucker-punched."

The Nationals opened a 5-0 lead in the top of the third inning, which seemed to be enough support to get Strasburg his 11th win. However, he didn't pitch the mandatory five innings for the decision, which went to Joe Blanton (1-2) after he retired Paul Goldschmidt and Chris Owings with runners on first and third and two runs already in during the fifth.

Washington batted around in the first while jumping on Ray for four runs. Goodwin led off with a long homer to center field -- an indication Ray would have another rough start against a team he has never beaten. The left-hander is 0-4 in four career starts against the Nationals.

"I felt like they kind of jumped on my pitches because I was missing everything over the middle instead of normally hitting my spots," said Ray, who needed 39 pitches to get through the difficult first.

After Goodwin hit his ninth homer of the season, off the center field batters' backdrop, Difo and Bryce Harper followed with sharply hit singles, and Ryan Zimmerman hit a sacrifice fly to center.

Ray got into further trouble by walking Daniel Murphy, leading to run-scoring singles by Anthony Rendon and Jose Lobaton.

Arizona shortstop Chris Owings' throwing error led to another run in the third. Washington rookie Adrian Sanchez grounded into a force play with the bases loaded for his first career RBI.

Difo hit his second homer of the season in the seventh.

Ray lasted five innings, giving up five runs -- four earned -- and six hits while striking out four and walking two.

Arizona cut the deficit to 5-2 in the fifth as Ketel Marte and David Peralta each singled in runs against reliever Matt Grace, who threw 42 pitches in 2 1/3 innings after making 31 pitches in relief on Friday. However, Blanton came in to shut down what might have been a big inning.

NOTES: Nationals RF Bryce Harper ran his hitting streak to 16 games with a single in the first inning. ... The Diamondbacks returned LHP Anthony Banda to Triple-A Reno after he pitched effectively at times (5 2/3 innings, four runs) during a 4-3 loss to Washington on Saturday night. ... Arizona RHP Taijuan Walker was reinstated from the paternity list and will start Tuesday vs. Atlanta. ... Diamondbacks OF J.D. Martinez (bruised left hand) hasn't started since being hit on the hand with a pitch during his Arizona debut on Wednesday, but he could be ready by Monday. He walked as a pinch hitter in the seventh inning Sunday. ... The Nationals are 14-5 vs. the NL West.