Arrieta (6-2) allowed one run and three hits in his first victory since June 30 at Boston. The 6-foot-4 right-hander has a 1.73 ERA in his last 11 starts, holding opponents to a .162 batting average.
The Cubs won three of four in a matchup of last-place teams. The Rockies have lost four of five and 11 of 15 overall.
Pedro Hernandez (0-1) allowed three runs and six hits in 5 2-3 innings in his first start for Colorado.
