Massey was scratched from the Royals' lineup ahead of Saturday's game versus the Cardinals due to back tightness, Anne Rogers of MLB.com reports.
Massey was originally in line to start at second base, but his back injury will force him to leave the starting nine. He's being viewed as day-to-day by the team, and he'll have the benefit of a scheduled off day Sunday to give him additional time to recover. In the meantime, Maikel Garcia will move over to the keystone Saturday while Paul DeJong covers third base and bats fifth.