Shota Imanaga struck out nine and didn't walk a batter in his six-inning major league debut and the host Chicago Cubs shut out the Colorado Rockies 5-0 on Monday.
Christopher Morel had two hits and Cody Bellinger had a two-run single to help Chicago win its home opener.
Charlie Blackmon, Brendan Rodgers and Ryan McMahon had singles for Colorado, which was outhit 9-3 and has lost four of five road games to begin the season.