The Nationals' best scoring opportunity against the veteran right-hander came in the second inning, when Jason Heyward's strong throw from right field prevented Adam LaRoche from scoring on Danny Espinosa's single.
Haren allowed four runs and eight hits in 5 1/3 innings. Most of his damage was incurred in the bottom of the second inning, which began with Juan Francisco's double and consecutive doubles by Chris Johnson and Tyler Pastornicky. Reed Johnson plated Pastornicky with a two-out single.
Haren retired the next 10 batters he faced following Johnson's double. But his run of good fortune ended when Justin Upton opened the sixth inning with a monstrous home run that sailed over the clock positioned at the top of the left-center field scoreboard.
Upton's fifth home run of the spring provided just enough cushion for left-handed reliever Luis Avilan, who surrendered hits to four of the seven batters he faced in Washington's three-run seventh inning.
Ian Desmond fueled the uprising with an RBI double and Danny Espinosa plated another run with a single.
Up next for the Nationals: The Nationals return to Space Coast Stadium on Friday to play the Tigers for the fourth time this spring at 1:05 p.m. ET on MLB.TV. Right-hander Stephen Strasburg will be on the mound for Washington. In his last start, Strasburg was dominant, lasting 5 1/3 innings and allowing one run on five hits while striking out eight batters. He threw 93 pitches, 64 for strikes. At one point, Strasburg struck out five consecutive hitters before Astros outfielder Rick Ankiel hit a 2-2 pitch over the right-field wall for his second home run of the spring.
Mark Bowman is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.