Duffy is out of the lineup for the first game of Tuesday's doubleheader with the Brewers.
Duffy had started each of the past three games at third base, going 3-for-12 with a walk, a run and a stolen base. The Cubs are deploying Frank Schwindel and Patrick Wisdom at first and third base, respectively, in the series opener with Milwaukee, and manager David Ross is expected to favor those two at the corner-infield spots for the time being. Duffy can play second base and left field, so there are other pathways to playing time.