Detroit scored 37 runs in a four-game sweep of Houston last weekend, but the Tigers were cooled off by Zimmernann (6-1), who became the first six-game winner in the National League.
Miguel Cabrera doubled home a run in the third to give Detroit a brief lead but Bryce Harper tied it on a sacrifice fly in the bottom half of the inning.
Washington went in front with an unearned run in the fourth and Harper hit his 10th homer of the season in the fifth to close out the scoring.
The Nationals have played six games in the month of May and have won five of them.
Boston schools pull out free condoms over wrapping complaints
Millions of Getty images now available for free via embed tool