Newton first injured his foot versus the New England Patriots in the third week of the 2019 preseason. If he doesn't practice on Wednesday, it's unlikely he'll play against the Cardinals.
The 2015 NFL MVP was brought along slowly this offseason because of shoulder surgery in late January, but was still hurt in an exhibition game.
The Panthers announced Tuesday that Newton wasn't at practice, and general manager Marty Hurney said it was due to the re-aggravation of a mild-foot sprain he suffered during the preaseason.
If Newton is ruled out for this weekend's game, second-year quarterback Kyle Allen will likely start. While Hurney said Newton is day-to-day, he also intimited there's no firm timline now for Cam, per Jourdan Rodrigue of The Athletic.
Allen has one career start - Week 17 a year ago.
Newton was particularly atrocious against the Buccaneers, as he went 24-for-50 with 324 yards.
Newton, who played his collegiate football at Auburn, was originally selected by Carolina with the first overall pick of the 2011 NFL Draft. Allen started Carolina's finale last season against the Saints and won the backup job this preseason.