Jayson Werth and Jeff Kobernus hit homered for Washington.
Ross Detwiler (2-5) took the loss in a game that started one hour, 10 minutes late because of rain. He allowed four runs and seven hits in six innings.
Jonathan Papelbon worked the ninth for his 14th save a night after blowing his first of the season and then getting the win.
CUBS 4, CARDINALS 2
ST. LOUIS (AP) — Ryan Sweeney and Cody Ransom hit back-to-back homers in a four-run first inning and that was plenty for Jeff Samardzija, who pitched the Cubs to the victory.
Chicago started fast against Adam Wainwright (10-4) and broke a five-game losing streak in St. Louis.
Pinch-runner Shane Robinson was called out for interference while trying to break up a double play to end the game.
Carlos Beltran hit his team-high 17th homer for the Cardinals, who lost for the third time in five games but still lead the majors with a 45-26 record.
Samardzija (4-7) gave up two runs and seven hits in 8 1-3 innings. Kevin Gregg got David Freese to ground into a game-ending double play for his 10th save.