KISSIMMEE, Fla. (AP) -- Gio Gonzalez tuned up for his World Baseball Classic start with a strong start for Washington.
The 21-game winner from last season doesn't expect to be around the Nationals after Sunday when he will join the United States for the WBC -- assuming the Americans advance to the elimination round.
"I'm still working on stuff, and I felt like I was building more strength," Gonzalez said Thursday after pitching three shutout innings in a 4-2 exhibition loss to the Houston Astros. "This time I was throwing the curveball, throwing the changeup for strikes, trying to get all three pitches in effect coming up on the Classic."
The 27-year-old left-hander is set up for Tuesday's start in his hometown of Miami.
"I've still got more work to do, more tuning up," he said. "I've still got to go out there and pitch more innings."
He threw 42 pitches against the Astros, giving up three hits while striking out three, and then threw 23 more pitches in the bullpen.
"I'm excited," said Gonzalez, who led the major leagues in wins in 2012 and finished third in the National League Cy Young vote. "I can't wait to join up with the team in Miami and just have some fun. Hopefully I can bring something to the team where we keep it nice and loose over there."
Astros starter Philip Humber gave up one hit in four innings, and Jason Castro drove in the winning runs with an eighth-inning single off losing pitcher Ryan Mattheus.
The 30-year-old Humber, who threw the 21st perfect game in big league history last April 22, took another solid step toward making the Astros' starting rotation in his second spring start.
"I'm still not where I want to be yet. I didn't throw all that many breaking balls, but that'll come," Humber said. "We're still pretty early, but I'm definitely pleased with what happened today."
So was manager Bon Porter, who is still looking for at least one more starting pitcher.
"Today was a great day all the way around," said Porter, who had criticized his team's erratic play earlier this week. "(We had) attention to detail, and it starts on the mound. ... Humber set the tone and everybody that came behind him followed it."
Corey Brown's bloop double was the only hit off Humber, who was released by the Chicago White Sox after going 5-5 season with a 6.44 earned run average last season.
"Right now the hitters are a little behind the pitchers, for the most part, so when the season comes I'm going to have to throw more off-speed pitches than I did today," he said. "But it was definitely a good sign; (the fastball) is the first thing to come usually and everything else follows after.
"I'm not concerned with results right now. Of course I'm trying to make my pitches, but . . . I'm focused on the process right now, and I feel good about where I'm at."
Castro's hit drove in Fernando Martinez, who had two of Houston's 11 hits, and Rick Ankiel.
Josh Zeid got the win for the Astros.
Michael Taylor drove in both of the Nationals' runs with an eighth-inning single off Zeid, who relieved Dallas Keuchel with the bases loaded.
NOTES: Paul Clemens pitched the ninth inning for a save . . . Houston first baseman Carlos Pena committed the game's only error when he lost Sandy Leon's high chopper in the sun, leading to an unearned run. "I just squeezed it too early, I think, or too late," Pena said . . . Jordan Lyles will start for Houston on Friday against the Braves . . . Jordan Zimmermann is scheduled to start for the Nationals against the Cardinals.