Marlins ace Jose Fernandez gave up one run in 4 1/3 innings while stretching his pitch count to 73.
Miami has already named Fernandez as its Opening Day starter. The right-hander was throwing hard, at 93-97 mph, but early on he was struggling with command, as he walked four to go along with his four strikeouts.
Nationals manager Matt Williams has not officially announced Strasburg as the Opening Day starter, but the hard-throwing right-hander is believed to be the choice.
Strasburg gave up two singles, including one to Rafael Furcal to lead off the first inning. But the ace was never really in trouble, and his afternoon was finished after 61 pitches. Strasburg's fastball was between 93-96 mph.
"It's just a natural progression," Strasburg said. "You want to go in the right direction. Obviously you're going to start out the first couple games of spring kind of feeling for it. I think mechanically I felt a lot more locked in this time."
The Nationals got to Fernandez for a run in the third inning on Zimmerman's sacrifice fly to left. Will Rhymes walked to open the inning, and he moved to third on Danny Espinosa's double.
"It was not my best," Fernandez said. "I was battling a little bit through it. I gave up only one run and kept the damage small. Obviously, not my best day, but I'm not worried about it or anything."
Fernandez was at 67 pitches through four innings, and he came out for the fifth to face one batter. He struck out Anthony Rendon.
Reliever Dan Jennings was hurt by an error that allowed Espinosa to reach, and the second baseman scored on Wilson Ramos' two-out single.
Up next: Sunday will be the Nationals' last split-squad day this spring. Matt Williams and his Major League staff will manage against the Tigers in the home game at Space Coast Stadium, where the club will go through its second test of the instant-replay system. Jordan Zimmermann will get the start against Detroit's Justin Verlander. Triple-A Syracuse manager Billy Gardner will lead the travel squad to Kissimmee, Fla., to take on the Astros, with lefty Gio Gonzalez taking on former Washington righty Brad Peacock. Both games will start at 1:05 p.m., with the home contest available on MLB.TV and the road tilt on Gameday Audio.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.