Carpenter exited Monday's game against the Cubs in the seventh inning with tightness in his back, Jenifer Langosch of MLB.com reports.
Carpenter ultimately had three unsuccessful at-bats Monday, with two strikeouts, before Matt Adams came in as a replacement at first base. The severity of the injury remains unclear, but Adams and Brandon Moss seem to be the top candidates to fill in if Carpenter requires added time off the diamond.