Mattison (undisclosed) was seen limping near the end of Tuesday's practice, Alec Lewis of The Athletic reports.
The nature of Mattison's issue isn't known, but the running back observed the latter stages of the session from the sideline before making his way to the locker room, per Kevin Seifert of ESPN.com. Kene Nwangwu (undisclosed) also didn't log any on-field work for a second consecutive day, which left plenty of RB reps for Ty Chandler and rookie seventh-rounder DeWayne McBride. Coach Kevin O'Connell will likely give an update on the state of the Vikings backfield in the near future, but for now Mattison's status is unclear.