Rooker isn't in the lineup for Thursday's game against the Cubs due to knee soreness, Martin Gallegos of MLB.com reports.
Manager Mark Kotsay said the decision to sit Rooker down for a day was precautionary, as the team didn't want to risk his soreness evolving into a more serious issue. Shea Langeliers will work as the Athletics' DH with Rooker on the bench, allowing Jonah Heim to start behind the plate.