Domingo Santana's two-out single to right field in the sixth inning gave the Brewers their first hit of the day off Cardinals starter Jaime Garcia.
The lefty stepped off the mound, then stepped back on and struck out Scooter Gennett to end the inning and notch his ninth strikeout of the game.
Garcia claimed his 10th strikeout in his 1-2-3 seventh, sitting down Jonathan Lucroy on an 84 mph changeup.
The 10 strikeouts ties Garcia's personal best. He's done it twice before, but not since April of 2013.
The Cardinals still lead 5-0.
Grichuk's questionable homer extends lead
For a moment, Randal Grichuk's first home run of the season looked like one really long out.