Westbrook is out of the lineup for Monday's game against the Mariners, Jen McCaffrey of The Athletic reports.
Westbrook had occupied the keystone in seven of the Red Sox's last eight games, but his surge in playing time was mostly fueled by Boston facing a schedule that was heavy on left-handed pitching. The 29-year-old still looks to be stuck in the short side of a platoon at second base with David Hamilton, who will cover the position Monday while the Mariners send right-hander Logan Gilbert to the bump.