Lohse (8-4) blanked the Orioles on four hits, walking one and striking out two before exiting after a 25-minute rain delay.
Lance Lynn came on after the delay to hurl two more shutout frames as the Cardinals took the first of a three-game set at Camden Yards.
The Orioles' Zach Britton (6-6) absorbed the loss, surrendering four runs on seven hits in a 5 2/3-inning start.
J.J. Hardy socked a solo homer for Baltimore.
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