WASHINGTON -- Jason Bay wasn't trying to hit a home run.
"The more you try, the harder it is," Bay said. "That was definitely the last thing on my mind, especially off Cordero. I was just trying to get on base -- a single, double, trying to get something going. For most guys, that's when the home runs happen -- when you're a little more relaxed."
Matt Capps (3-2) got six straight outs to complete a three-hitter, just the third victory for Pittsburgh in its last nine games.
For only the second time in six chances this season, the Pirates won a three-game series in which they split the first two games. After the game, they headed to New York for a weekend interleague series at Yankee Stadium.
The Nationals, who finished a 3-6 homestand, had some controversy when manager Manny Acta removed second baseman Felipe Lopez for failing to run out a ground ball to second base in the fifth inning.
"I love Felipe," Acta said. "I've known Felipe longer than anybody in this locker room ... but that being said, he's under everybody's rule.
"We said it from the beginning: we're going to play hard. We're going to play right, and we're probably going to have to outhustle the opposition. It's not going to be tolerated, regardless of who you are."
It was the second time this season Acta benched a starter for not hustling. He pulled Ryan Church for not running out a ground ball against Florida on Apr. 23.
Lopez declined to speak to reporters after the game.
Bay's 11th home run of the season was the first run Cordero surrendered since returning from the bereavement list on May 14, a span of 13 appearances.
"If you're going to get beat here late in the game, we want to get beat opposite field," Acta said. "If a guy hits a ball out opposite field, right-center-field, at RFK, you've just got to tip your hat to him. Jason Bay is a good power hitter."
Bay didn't crush the 1-1 pitch, but he got enough to clear the 380-foot mark.
"I didn't know if it got high enough in this big ballpark," Bay said. "I think screaming at it to go over helped a little."
Pirates starter Ian Snell struck out seven in seven innings, allowing two runs, three hits and three walks. He gave up a two-run homer to Dmitri Young in the first but kept Pittsburgh in the game. He threw only 86 pitches, 54 of them strikes.
"They were just swinging at everything," Snell said. "When you get players swinging at everything, you're going to get a lot of ground balls and flyouts."
Washington's Matt Chico gave up two runs, four hits and three walks in seven innings. He surrendered a two-run homer to Freddy Sanchez that tied the score in the third. It was the defending NL batting champion's first home run in 354 at-bats since Aug. 23.
The Pirates squandered several chances to score. Rajai Davis led off the game with a triple but was stranded there after a pair of flyouts and a strikeout, and Ronny Paulino was thrown out at the plate to end the second by left fielder Ryan Chuch while trying to score on Jack Wilson's double. Catcher Brian Schneider tagged Paulino's shin when the runner didn't slide.
Nate McLouth was stranded at third in the eighth when Sanchez hit an inning-ending grounder.
Pirates OF Xavier Nady did not play after injuring his left hamstring Wednesday. He was available to pinch hit, though, and manager Jim Tracy said Nady might be the designated hitter during interleague play. ... Sanchez hit six homers last year. ... Chico's five strikeouts were one shy of his season high. He did not get a decision for the fifth time in six starts.