Washington snuffed out its own ninth-inning rally in a 3-2 loss at Miami on Saturday.
The Nats (26-17) got a run-scoring single by Wilson Ramos and loaded the bases with nobody out off Marlins closer A.J. Ramos.
Jayson Werth hit into a 5-2 double play, and Jose Lobaton grounded out to first to kill the rally.
Jose Fernandez (6-2, 3.02 ERA) earned the win, giving up a run on four hits in six innings of work, striking out nine and walking one.
Joe Ross (3-4, 2.89 ERA) took the loss for the Nationals, giving up three runs on eight hits in five and two-thirds innings, striking out seven and walking two.
Ben Revere, Bryce Harper and Daniel Murphy each had two hits for Washington.