LeMahieu is dealing with groin tightness, which is why he is not in Saturday's lineup against the Red Sox, Kristie Ackert of the New York Daily News reports.
He had an MRI on Saturday, and manager Aaron Boone does not think it is a major injury, per Ackert. Gio Urshela is starting at third base in his stead and would figure to continue to get starts at the hot corner if LeMahieu needs more than one day off.