The Rays plan to call up Slater from Triple-A Durham, Marc Topkin of the Tampa Bay Times reports.
Signed to a minor-league contract in late May, Slater has a 1.160 OPS in six games with Durham. The Rays are slated to face three left-handers in their early-week series versus the Red Sox, so the right-handed-hitting Slater should get some reps in the outfield. Slater has slashed just .209/.286/.233 through 49 plate appearances in the majors this season.