Mitchell (undisclosed) remained a non-participant in Thursday's practice, Kris Rhim of ESPN.com reports.
With Mitchell now having missed six straight practices, his status for Week 1 against the Cardinals is starting to come into question. If he's unable to go against Arizona, Kimani Vidal would settle in as the likely RB2 behind Omarion Hampton. Mitchell will need to get back on the field in some capacity next week if he's going to have a chance to suit up for the regular-season opener.