WASHINGTON -- Colorado Rockies rookie German Marquez got roughed up by the Washington Nationals back in April when he made his first start of the season.

He has come a long way since then.

Marquez pitched seven strong innings, Trevor Story homered and the Rockies defeated the Nationals 4-2 on Saturday night in the opener of their three-game series.

Marquez (9-4) allowed two runs and three hits and struck out a career-high 10 batters without issuing a walk.

"German set the tone with an ultra-aggressive mindset of just throwing good strikes. I saw the confidence grow from the first hitter of the game. Really good breaking ball, good velocity," Rockies manager Bud Black said. "You saw some funny swings on the breaking ball. Once they had to honor the breaking ball, the fastball became much more effective."

On April 25 against the Nationals, Marquez allowed eight runs in four innings of a 15-12 loss. Saturday night, he became the third rookie in the majors this season to win nine games, one behind teammates Kyle Freeland and Antonio Senzatela, as he won his fourth consecutive start.

"I feel more confident now, more experienced and I was facing one of the best teams in baseball and you have to step up," Marquez said through an interpreter.

The 22-year-old Marquez didn't allow a baserunner until Matt Wieters lined a one-out single to left in the sixth inning. Howie Kendrick, in his first plate appearance for Washington, followed with a shot to the wall in left-center field for a pinch-hit double, moving Wieters to third.

After Brian Goodwin struck out, Wilmer Difo blooped a single just inside the left-field foul line and both runners scored to pull the Nationals (61-40) within 4-2. Marquez then fanned Bryce Harper to end the inning.

Pat Neshek pitched a perfect eighth in his Rockies debut and Greg Holland worked a 1-2-3 ninth for his major league-leading 32nd save.

Gerardo Parra had two hits for Colorado (59-45), which snapped a three-game losing streak. He has now hit safely in 13 of 14 games since coming off the disabled list on July 7.

Harper saw his 19-game hitting streak snapped as Washington's Nos. 3-6 hitters (Harper, Ryan Zimmerman, Daniel Murphy and Anthony Rendon) went 0-for-13.

Washington's Tanner Roark (8-7) was coming off two strong outings, but control problems hurt his effort. He allowed four runs and five hits in five innings, walking four -- one intentionally -- while striking out eight. Two of those who walked came around to score.

"He was wild wide off the plate. Every time he tried to go away, it'd be off the plate," Nationals manager Dusty Baker said. "Tonight his pitch count got high, he had four walks -- which is quite a bit for him -- so he just wasn't sharp tonight."

Marquez was perfect through five innings against the National League East leaders, striking out seven.

"He got rolling there the first time through the lineup," Wieters said. "He had upper 90s with a good breaking ball and he was locating pretty well."

In the fifth, Murphy hit a ball barely foul to the third deck off Marquez before striking out.

Roark opened the second inning by walking Carlos Gonzalez on four pitches, and Story homered to center on a 2-2 pitch to give Colorado an early 2-0 lead. It was Story's 15th home run of the season.

"That was a really solid at-bat and he got a ball out over the plate and hit the opposite-field homer," Black said. "Trev's had better at-bats the last month."

In the fifth, DJ LeMahieu drew a one-out walk. With two outs, Parra and Mark Reynolds hit back-to-back doubles to make it 4-0.

NOTES: Colorado activated closer Greg Holland from the paternity list and recalled OF Raimel Tapia from Triple-A Albuquerque. The Rockies optioned RHP Carlos Estevez to Albuquerque and RHP Jordan Lyles was designated for assignment. ... Washington RHP Stephen Strasburg, on the 10-day disabled list with right elbow nerve impingement, threw a bullpen session Saturday. ... The Nationals activated INF/OF Howie Kendrick a day after acquiring him from Philadelphia and placed INF Stephen Drew on the 10-day disabled list with a left abdominal strain. ... Because of Friday night's rainout, the teams will close out the series with a split doubleheader Sunday.