Arrieta (1-0) struck out seven and walked three. He was 10-5 with a 2.53 ERA in a breakout 2014 and improved to 3-0 with a 0.74 ERA in six career starts against St. Louis.

Phil Coke, Neil Ramirez, Pedro Strop and Hector Rondon combined for hitless relief. Rondon pitched a perfect ninth for his first save this season with the Cubs, who lost 3-0 to St. Louis on Sunday night’s opener.

Lance Lynn (0-1) struck out nine in six-plus innings, allowing both runs — one earned — and two hits. Castro’s single chased him in the seventh, and Miguel Montero hit a sacrifice fly off Kevin Siegrist.