Stanton mashed his 51st homer of the season and 18th this month, matching a Major League record in the month of August. But Nationals right-hander Edwin Jackson limited the damage following the first-inning home run, giving up three runs (two earned) while pitching into the seventh inning.
Miami dropped back-to-back games for the first time since Aug. 9-10 (also to Washington) after it opened the day trailing the Rockies by 4 1/2 games for the second National League Wild Card spot.
Marlins right-hander Vance Worley entered having beaten the Nationals twice this month while allowing just one run in 13 innings in those two starts.