Kopech tossed a scoreless ninth inning in Sunday's 7-3 win over the Cardinals, allowing one hit with no walks and one strikeout.
Kopech gave up a single on his first pitch but went on to retire the Cardinals' top three hitters in order. The 29-year-old threw seven of nine pitches for strikes in his first appearance since returning from the injured list Saturday. He'll likely continue to be eased back in before joining the mix for high-leverage innings.