Strasburg (4-6) pitched well in his return to action last Sunday, but suffered a 2-0 loss to Cleveland.
He received limited run support again Friday, although it was enough to bring the Nationals their third straight win.
Strasburg struck out nine in a seven-inning effort and gave up a run in the third after hitting leadoff batter Josh Rutledge. A two-out single by DJ LeMahieu brought home Rutledge.
Ryan Zimmerman doubled in the tying run in the sixth and Ian Desmond put Washington in front in the seventh with his 12th home run of the year. Desmond has hit a homer in each of his last three games.
Rafael Soriano allowed a one-out single in the ninth, but retired the next two batters for his 19th save.
Colorado reliever Manny Corpas (0-2) gave up the home run to Desmond and thus took the loss.