Happ allowed only three singles and won for the fourth time in six starts since being acquired from Seattle at the July 31 trade deadline. He retired 15 straight batters in one stretch, matched his season-high with eight strikeouts and walked none. Happ (4-1) lowered his ERA with the Pirates to 1.57.
Pittsburgh ended a four-game losing streak and cut St. Louis' lead in the NL Central to 5 1/2 games. It was the Pirates' fourth win in their last 17 games at Busch Stadium.
Carlos Martinez (13-7), pitching for the first time in eight days, gave up four runs and seven hits and three walks in five innings.
