Mountcastle is out of the lineup for Sunday's game against the Guardians.
Mountcastle will get a breather for the series finale in Cleveland after he had started in each of the Orioles' last eight games while going 8-for-33 with three extra-base hits, nine RBI and four runs. He'll cede his spot in the lineup to trade-deadline pickup Eloy Jimenez, who serves as the Orioles' designated hitter while Ryan O'Hearn fills in for Mountcastle at first base.