Morton escaped with four runs allowed, three earned, in 4.1 innings, but it actually could have been far worse - he allowed five walks and seven hits, and the defense behind him was hideous. But the Cubs consistently failed to blow the game open.
Carlos Pena's fielder's choice led to a run in the third on a throwing error by Ronny Cedeno, and the Cubs added a run in the fourth and two more in the fifth.
Tony Watson continued Morton's walk-happy ways in the sixth, leading to another run on a single by Bryan LaHair.
The Pirates made it 5-3 on a two-run homer by Neil Walker in the eighth, that was all they got, and the Cubs added an insurance run in the bottom of the inning.