After cruising through the first two frames, Nationals starter Dan Haren ran into some trouble against the bottom of the Houston order in the top of the third.
Astros catcher Carlos Corporan singled to start the rally, then leadoff man Tyler Greene later walked with two outs. A Jose Altuve line-drive single to left field broke the scoreless tie.
But the Nationals battled back against Houston starter Lucas Harrell in the bottom of the inning when Danny Espinosa singled to lead off the frame, stole second base and came around to score on a Jayson Werth grounder through the hole at shortstop.
Both pitchers left the game with the score tied at 1, as Haren gave way to Zach Duke in the fourth and Harrell was replaced by Ambriz in the fifth.
Haren threw 50 pitches in three innings, surrendering the one run on two hits and one walk while striking out two. Harrell also allowed just one run, scattering three hits and one walk while striking out four. He threw 61 pitches (36 for strikes) over his four innings of work.
"I felt good," said Haren. "The first couple innings went real quick. After that, I had a long third inning, which is probably what I needed here. Throw some out of the stretch, get extended. Probably a little bit fatigued, but that's a good thing. Overall, I feel healthy. I got some good looks and can just build off it."
Harrell has been working on his curveball this spring, and was pleased with the outing.
"I really worked on [the curve] the last couple of days, really worked on it a lot this offseason trying to get it better," said Harrell. "Corporan and I were on the same page the whole time, and then the defense made some good plays."
Haren was throwing to Wilson Ramos, who made his first appearance behind the plate since he tore the ACL in his right knee on May 12 of last year. Ramos struck out in his only at-bat, and appeared to have little difficulty behind the plate in his three innings of work.
The Nationals put up five runs in the sixth, when Espinosa knocked a two-run single, Tracy added a sacrifice fly, and two runs scored on Corey Brown's RBI single and a throwing error by Houston center fielder Justin Maxwell on the play.
Newly acquired Nationals reliever Rafael Soriano, expected to step in and take over the closer role this season, also made his first appearance of the spring in the seventh, allowing one hit and striking out one in one scoreless inning of work.
Up next: Washington will make the trip to Clearwater on Wednesday to take on the Phillies for the first time this spring in a 1:05 p.m. ET matchup that will feature Stephen Strasburg taking on Roy Halladay. Nationals position players making the trip include Denard Span, Anthony Rendon, Micah Owings, Tyler Moore and Matt Skole. Fernando Abad, Yunesky Maya, Erik Davis and Cole Kimball are scheduled to throw behind Strasburg.