Harris (oblique) didn't practice Thursday, Teresa Varley of the Steelers' official site reports.
Harris, who suffered an oblique injury against the Colts this past Monday, now has missed back-to-back sessions, though a return to practice in any capacity Friday would boost his chances of suiting up Sunday against the Falcons. If Harris ends up out or limited this weekend, though, Jaylen Warren -- a full participant for the second day in a row after being inactive Week 12 -- would be in line for an expanded role versus Atlanta.