DENVER -- When Jason Marquis got in a jam, he kept his cool.
"In the past, I was so worried about guys not scoring -- trying to make perfect pitches, and trying to get three outs with one pitch," said Marquis, who extended his scoreless-innings streak to 17. "This year, I told myself to bear down and focus on the hitter, not let it get out of hand."
It was the eighth 1-0 game in Coors Field history, the only run produced by Todd Helton's RBI double in the first inning.
Who could have figured that run would hold up?
"You never know what to expect," Marquis said, laughing. "I'm glad they got a run on the board early, makes our job a little bit easier."
Marquis was effective early and resourceful late, pitching out of bases-loaded jams in the seventh and eighth innings.
Marquis (11-5), who allowed seven hits and struck out three, was coming off a two-hit shutout at Los Angeles on June 30.
Huston Street threw a perfect ninth for his 20th save in 21 chances.
Rookie Craig Stammen (1-4) went a season-high seven innings, giving up five hits and the one run.
A sinkerball pitcher like Marquis, Stammen said he aspires to similar results.
"He's a guy I need to be like in the future, take my team deep in ball games," Stammen said. "He's an All-Star and he got rewarded that for a reason."
With two outs and the bases loaded in the eighth, Marquis got Josh Willingham to fly out to right.
In the seventh, he faced an even stickier situation after Adam Dunn led off with a double and Willingham followed with a single, advancing Dunn to third. Cristian Guzman hit a high comebacker to Marquis, who plucked it out of the air and picked off Dunn at third after he lurched too far down the line.
Josh Bard then singled to right, but third base coach Pat Listach held up Willingham, loading the bases.
Marquis made his best pitch of the game to Ronnie Belliard, who grounded into an inning-ending 6-4-3 double play.
"Slider, down and away," Marquis said. "I was able to make a quality pitch."
Marquis' teammates have come to expect big wins out of him since he was acquired from the Chicago Cubs in January. On Monday, he stopped the Rockies' two-game losing streak.
"He's definitely been a blast to play behind," said Clint Barmes, who scored the lone run. "He attacks the zone, getting great movement. He gives the infielders a lot of work and makes it fun."
Right fielder Brad Hawpe's strong arm made the Nationals cautious about sending runners, especially Willingham in the seventh. Had Willingham gone, there's little doubt he would have been out as Hawpe threw a perfect strike to the plate.
"Something that may go by the board -- and I'm not going to allow it to do so -- is our right fielder," Rockies manager Jim Tracy said. "Brad Hawpe's play, not only the throw but coming to get the ball as quickly as he did. ... Jason pitched extremely well and we defended extremely well."
Stammen pitched his way out of potential messy situations as well, none bigger than escaping a two-on, one-out jam in the fifth to keep the game close. He struck out Marquis and then got Dexter Fowler to lift an easy fly to right.
"He made pitches all day," Nationals manager Manny Acta said. "He kept his sinker down and wasn't intimidated by the altitude here."
"He was outstanding," Acta said.
Rockies reliever Manuel Corpas (right elbow bone spurs) threw a 25-pitch bullpen session Monday without any pain. ... Helton's double was the 494th of his career. ... Marquis tied the franchise record of 11 first-half wins, sharing the mark with Aaron Cook (2008) and Shawn Chacon (2003).