Walker is not in the lineup for Monday's game against the Cubs.
It's righty Ben Brown on the hill for the Cubs, marking the third time in six games versus right-handers since Walker returned from the injured list that he's been out of the lineup. He was also absent from the lineup once over that span against a left-handed opener. Alec Burleson is in right field and Nolan Gorman is at designated hitter for the Cardinals.