Mateo is not in the starting lineup for Wednesday's series finale with the Red Sox, Rich Dubroff of BaltimoreBaseball.com reports.
Mateo will get a breather after he went 2-for-7 with a solo homer, a double and three runs scored over the first two games of the series. Gunnar Henderson will take over at shortstop while Ryan O'Hearn enters the lineup at first base and bats seventh against Boston.