Milwaukee center fielder Lorenzo Cain soared above the wall to rob Jose Martinez of a tying home run for the final out, lifting Christian Yelich and the Brewers over the St. Louis Cardinals 5-4 in an opener Thursday. Young right-handers Jack Flaherty and Freddy Peralta get the ball when the series resumes tonight. St. Louis is counting on the 23-year-old Flaherty to help anchor the rotation after he went 8-9 with a 3.34 ERA in 28 starts last year. Peralta, who turns 23 in June, won a spot in Milwaukee’s rotation during spring training. He went 6-4 with a 4.25 ERA in 16 appearances last season during his first year in the majors, including 14 starts.