Cubs 4, Pirates 0
CHICAGO — Jake Arrieta pitched seven dominant innings and homered in his majors-best 21st win to help stop the Pirates' eight-game win streak. Arrieta retired the first 18 batters before Gregory Polanco grounded a leadoff single to left in the seventh. It was Pittsburgh's only hit of the game. Arrieta homered in the second and struck out nine while improving to 15-1 with a 0.89 ERA in his past 19 starts.