The score was tied at 3-3 when Washington went ahead to stay in the fifth inning against right-hander Bryan Evans. Nate McLouth led off with a single and scored on a triple by Jeff Kobnerus. Ian Desmond followed with a groundout, but Kobernus scored on the play to make it 5-3.
The Nationals added to their lead by scoring four more runs in the bottom of the seventh. Matt Skole highlighted the scoring with a two-run double. The runs were charged to left-hander Edgar Olmos.
The Marlins had a 2-1 lead after three innings, when right-hander Chris Young allowed a solo home run to Ed Lucas.
Marlins left-hander Brian Flynn was on the mound when first baseman Adam LaRoche hit a two-run homer to give the Nationals a 3-2 lead.
But Miami would tie the score at 3-3 in the fifth inning off reliever Craig Stammen. Greg Dobbs scored on a double by Donovan Solano.
Marlins starter Brad Hand went two innings, allowing one run on two hits with two strikeouts.
Up next: The Nationals travel to Tampa on Monday to play the Yankees. Ross Detwiler will get the start and pitch at least two innings. The Nationals are hoping that he mixes his pitches. Last year, Detwiler threw his fastball 88 percent of the time. Tanner Roark, who is also competing for the fifth spot in the rotation, is expected to pitch in the game.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.