Mack (calf) was listed as a non-participant in what coach Frank Reich classified as a "modified practice" Wednesday, Andrew Walker of the Colts' official site reports.
The report described the session as an "up-tempo walkthrough." Meanwhile, Joel A. Erickson of The Indianapolis Star relays that the running back walked through the locker room Tuesday carrying a walking boot (as opposed to wearing it), but told reporters that he'd be fine. Though updates here are worth revisiting Thursday, at this stage his status for Sunday's game against the Falcons does not appear to be in danger.