Molina, who socked a game-tying, ninth-inning homer for the Cards in the their 8-7 defeat of the Marlins Monday, struck again early in Tuesday's contest, lining a 3-2 Carlos Zambrano offering off the left-field scoreboard.
Kyle Lohse (4-6) made the lead hold up, surrendering just two runs on four hits over 7 1/3 frames while walking two and striking out four.
Jason Motte collected his 16th save for the Cardinals.
All five runs allowed by Zambrano (4-6) were unearned. The Miami right-hander committed a throwing error in the decisive first inning, and finished by yielding seven hits and five walks over 6 2/3 frames.
Giancarlo Stanton socked a solo homer for the Marlins.