The Marlins, who pulled off a three-game sweep of the Nats, reached the midway point of their six-game homestand. The Fish will host the Boston Red Sox tomorrow.
Miami(67-64) struck first in the opening frame to go up 1-0. Heriberto Hernandez doubled into the left-field corner and Agustin Ramirez scored.
Washington(61-71) evened it up 1-1 in the top of the fourth. Dylan Crews doubled to deep center field which brought in Daylen Lile.
The Marlins moved in front 3-1 in the fifth ining. Xavier Edwards singled into left field to score Otto Lopez and Ramirez.
The Nationals closed it to 3-2 in the top of the sixth. Jorbit Vivas doubled off the right-field wall and Keibert Ruiz reached home.
It became 5-2 for the Fish during the bottom of the sixth. Joe Mack sliced a double down the left-field line and Jakob Marsee crossed the plate. Lopez came up next and hit a sacrifice fly to right field and Griffin Conine touched home.
The Nationals gave up another run in the eighth inning and trailed 6-2. Marsee scored on a force out to second by Mack.