Second baseman Jedd Gyorko sent his fifth home run of the season over Busch Stadium's left field wall to give the Cardinals a 2-0 lead over the Diamondbacks in the second inning.
The 384-foot line drive came on a 2-0 fastball from Diamondbacks starter Robbie Ray and scored Matt Adams, who reached on a throwing error by third baseman Jake Lamb.
The Cardinals have knocked 56 homers this season. They entered Saturday one behind the National-League-leading New York Mets (57). The Diamondbacks' 52 rank third.
Grichuk strikeout strands three
A Randal Grichuk strikeout stranded three Cardinals in Saturday's first inning.