Gio Gonzalez was tagged for six runs on 10 hits in five-plus innings on Sunday, and the Nats couldn’t break through on Miami starter Dan Haren in a 6-2 loss.
The loss was the fifth in a row for Washington, which falls to five games under .500 and seven and a half games behind the National League East-leading New York Mets.
The Nationals took the lead early on a second-inning solo homer by Bryce Harper, his fifth of the season, but Miami answered in the fourth with a two-out, three-run triple by Adeiny Hechavarria.
An RBI single in the fifth from Denard Span cut the Miami lead to 3-2, but the Marlins got two in the bottom of the fifth on an RBI triple by Giancarlo Stanton and a sacrifice fly by Marceli Ozuna.
An Ichiro Suzuki RBI single in the sixth chased Gonzalez (1-2).
Haren (2-1) got the win, giving up two runs on two hits in five innings.