Mullins is out of the lineup for Wednesday's game against the Reds, Ryan Bass of Rays.tv reports.
Mullins had started in each of the Rays' last seven games, but the left-handed-hitting outfielder will take a seat for the series finale while the Reds send southpaw Brandon Williamson to the mound. Over 20 plate appearances against lefties this season, Mullins has slashed .176/.263/.176.