WASHINGTON (AP) -- Roy Oswalt showed his arm is still plenty good enough to help deliver some much needed innings for the Colorado Rockies.
He'd prefer, however, to cut down on his strikeouts.
Jordan Zimmermann pitched eight innings to win his 10th game, Adam LaRoche had three hits including a two-run triple and the Nationals spoiled Oswalt's return to the majors with a 5-1 win Thursday night.
Todd Helton and DJ LeMahieu had two hits for the Rockies, who have lost the first four games of a nine-game road trip and fell to .500 for the first time since April 2.
Oswalt (0-1) went five innings in his Rockies debut, allowing four runs on nine hits. He threw 101 pitches, struck out 11 and didn't walk a batter.
"I felt strong," Oswalt said. "Overall felt pretty well just, it's hard to say this, but really too many strikeouts. Kind of got my pitch count up and I was trying to get deeper into the game."
The 35-year-old right-hander was signed to a minor league contract May 2, and went 3-2 with a 2.16 ERA in five starts for Double-A Tulsa before being called up.
"I'm not going to come up here and embarrass myself. If I felt like I couldn't give a team a chance to win I wouldn't come back," Oswalt said. "I feel like I can still start. Ninety pitches into the game I felt just as strong as the first 10."
Colorado manager Walt Weiss was impressed with the Oswalt's effort.
"I thought Roy threw the ball extremely well, punched out 11 in five innings," Weiss said. "Plenty of stuff, plenty of arm, a really good fastball. I thought he had a few tough breaks, the line could have been better than what it showed."
Washington hitters agreed.
"He's still got it," Nationals catcher Kurt Suzuki said. "His fastball has some life to it. It looked like he had a pretty good curveball going. He's still got it in the tank, that's for sure."
Ian Desmond, who hit a grand slam in the 11th inning of Wednesday's 6-2 win at Philadelphia, homered his first time up Thursday night to put Washington ahead 1-0 after two.
LaRoche led off the Washington fourth with a single. After Oswalt fanned Jayson Werth and Desmond, Lombardozzi singled. Suzuki then hit a grounder between third and short that shortstop Jonathan Herrera managed to deflect. Herrera retrieved the ball in short left, but LaRoche raced around from second and was safe on a close play at home to make it 2-0.
LaRoche provided some insurance in the fifth when he tripled with one out, scoring Denard Span and Anthony Rendon.
Zimmermann drove in the Nationals' fifth run with a sacrifice fly -- the first of his career -- in the sixth.
On the mound, Zimmermann (10-3) allowed an unearned run on six hits, returning to form after surrendering six runs and eight hits in five innings Saturday in Cleveland.
"He's throws strikes with all his pitches," Weiss said of Zimmermann. "When you've got a big arm and throw strikes, you're going to be tough."
Zimmermann retired 16 straight in one stretch, throwing 112 pitches -- 85 for strikes -- while fanning nine and walking one.
"I felt like I threw the ball well and had good fastball command, my slider was good and I got a big strikeout in the last inning there on a changeup," Zimmermann said.
"I was throwing strikes and getting ahead of guys. I know they're an aggressive team and that kind of works in my favor. Throw some first-pitch strikes and let them hit the ball."
Colorado finally got to Zimmermann in the eighth. Pinch hitter Josh Rutledge singled, Rendon committed a throwing error after fielding Tyler Colvin's grounder and Rutledge ended up on third. LeMahieu singled to score Rutledge, but Zimmermann struck out Carlos Gonzalez on a changeup and Michael Cuddyer to end the threat.
NOTES: Cuddyer extended his hitting streak to 18 games. ... To make room for Oswalt, the Rockies optioned LHP Jeff Francis to Triple-A Colorado Springs and designated RHP Chris Volstad, who was at Colorado Springs, for assignment. ... Rockies CF Dexter Fowler (right ring finger) missed his third straight game. ... Colorado RHP Tyler Chatwood (4-1, 2.33) opposes Stephen Strasburg (3-6, 2.50) Friday.
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