The Astros scored five runs on four hits off Clippard -- three for extra bases -- and two walks in their final at-bat for the dramatic win.
Brett Myers -- who has a solidified spot in the Astros' rotation -- and Ross Detwiler -- competing to be the No. 5 starter for the Nats -- each struggled at Osceola County Stadium.
On a day featuring several early hard-hit balls, Myers yielded six runs (five earned) on eight hits in five innings, but threw 61 of his 83 pitches for strikes. Detwiler, meanwhile, fell short of his target of five innings because of a high pitch count and wound up giving up three runs in three frames, moving his spring ERA to 3.00.
2010 Spring Training - null
Sights & Sounds
Spring Training Info
The Astros pushed Detwiler's pitch count up with three runs in the second, thanks to RBI singles by Matt Downs and Humberto Quintero and a sacrifice fly by T.J. Steele.
Nats catcher Wilson Ramos gave his club a four-run cushion with an eighth-inning solo homer to center off Wesley Wright.
Washington infielder Alex Cora went 2-for-4 with two runs scored to move his Grapefruit League batting average to .429. Houston outfielder Jason Michaels went 2-for-3 and is batting .400.
One of the Nationals' top prospects, Cole Kimball, pitched two scoreless innings, striking out three and walking two, and now has a 1.13 ERA in eight innings.
Astros slugger Carlos Lee started his first Grapefruit League game at first base, going 0-for-3.
Up next for Nationals: On Thursday, the Nationals travel to Walt Disney World to play the Braves for the second time this spring at 6:05 p.m. ET on MLB.TV. The last time these two teams met was March 4, with Atlanta blanking Washington, 5-0. Yunesky Maya will get the start for the Nats. He is competing with three others -- Detwiler, Chad Gaudin and Tom Gorzelanny -- for the fifth spot in the rotation.
Up next for Astros: After an off-day Thursday, the Astros face the Marlins in Jupiter, Fla., at 12:05 p.m. CT on Friday. Getting the start will be J.A. Happ, who sports a 3.38 ERA in eight innings. His last time on the hill, the 28-year-old lefty yielded his only three runs of the spring in four innings to the Orioles. Michael Bourn, who hasn't played since Sunday while feeling under the weather, will try to play as well. Starting for the Marlins will be right-hander Ricky Nolasco.
Alden Gonzalez is a reporter for MLB.com. Read his columns and his blog, listen to his podcast and follow him on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.