The win in Arlington completed a three-game sweep.
The Rangers didn't score until Hank Blalock led off the ninth against closer Brandon Morrow (0-3) with a home run into the second deck of right-field stands.
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Matt Harrison (4-2) threw a five-hitter for his second complete game in a row, though his consecutive scoreless innings streak ended at 22.
Harrison struck out seven with no walks, but left the mound after his 102nd pitch trailing 2-0.
Michael Young had two hits for Texas -- singles in the first and sixth. After his first single, Josh Hamilton walked before Hernandez retired 15 of the next 16 batters.