Washington scored nine runs in the bottom of the first, and Nats starter Gio Gonzalez put it on cruise control from there in a 9-2 win over the Pittsburgh Pirates that completed a three-game Nationals sweep.
Gonzalez (5-4) went seven easy innings, giving up four hits and walking two while striking out four Pirates hitters.
Washington (37-33), which now leads the New York Mets by a game in the National League East, got all of its offense in the first, touching up Charlie Morton, who had come into the game with a 5-0 record and 1.62 ERA, for nine runs on eight hits in two-thirds of an inning, sending his ERA soaring all the way up to 3.97.
Bryce Harper hit his 24th homer of the year, a two-run shot, in the deluge, and Yunel Escobar had a three-run shot later in the inning to chase Morton.