Latos (2-0) scattered five hits, worked around three walks and struck out four en route to the victory, his second straight after beginning the season with four consecutive no-decisions.
Aroldis Chapman followed with a 1-2-3 ninth to notch his sixth save as the Reds took the opener of a three-game road series.
St. Louis starter Adam Wainwright (4-2) surrendered two runs on five hits over seven innings, walking two and striking out six.
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