The Nationals scored four times in the seventh to take a 5-4 lead, but Houston tied it in the eighth and won it in the ninth on Blum's bases-loaded hit.
Joe Beimel (0-5) was on the mound to open the ninth and he gave up a leadoff single to Tejada. After Beimel retired a batter, he was relieved by Mike MacDougal.
Carlos Lee flew out deep to center, allowing Tejada to tag up and go to second. Hunter Pence drew an intentional walk and Ivan Rodriguez walked on a 3-2 pitch to load the bases.
That brought up Blum, who drove in the game-winning run with his third hit of the night.
Houston had tied the game in the eighth on a sacrifice fly by Jeff Keppinger.
The win went to Jeff Fulchino (3-3), who survived the top of the ninth when Washington's Willie Harris was thrown out at home trying to score from second on a single to center by Nyjer Morgan.
The Nationals staged their seventh-inning comeback thanks to a two-run double by Josh Willingham and RBI singles from Willie Harris and Cristian Guzman.
Copyright 2009 by United Press International.
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