The Cardinals needed the two blasts and a two-run double by Kolten Wong to help hold off the Brewers' late offensive push. Hernan Perez's RBI single chased Weaver in the seventh, and Jesus Aguilar pulled Milwaukee to within one with an eighth-inning, pinch-hit homer that snapped reliever John Brebbia's streak of 14 straight scoreless appearances.
Molina's three-hit performance spoiled the night for Brewers starter Brent Suter, who allowed as many runs (five) over 5 1/3 innings on Wednesday as he had over 30 innings in July.
Weaver pitched a career-best 6 1/3 innings and limited the Brewers to two runs on five hits, including Eric Thames' 25th home run of the season in the first inning.