Manager Manny Acta said that Sizemore "locked up his back" Sunday morning and that he felt enough discomfort in the clubhouse and in the batting cages that Acta and the team's training staff elected to rest him on Sunday.
Michael Brantley replaced Sizemore in center field during Sunday's 9-8 loss to Detroit and batted second, going 1-for-5. Austin Kearns started in left field and went 1-for-4 with a double.
It won't be known if Sizemore will be available for the Tribe's home opener until Monday morning, but the injury doesn't appear to be serious.
"We're anticipating that he'll be ready to go," Acta said.
Mike Scott is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.