The star quarterback did not throw during practice on Tuesday, seeing the field briefly at the end of the session to hand off.
Coach Ron Rivera told reporters after practice that Newton started warming up in the morning and felt sore. The team didn't want to push the quarterback, who is coming off shoulder surgery.
"He started warming up this morning and said he still felt a little bit sore," Rivera said, via Max Henson of the team's official website. "Why push it? Why have him throw with a sore arm and make it worse?
"It made no sense to have him throw with a sore shoulder."
It makes sense for the Panthers to play it safe with Newton, who didn't start throwing until mid-June. Carolina likely will hold out Newton periodically through camp. There is no benefit to pushing him back quickly, especially if he feels sore.
Newton wasn't the only starter to miss practice. Left tackle Matt Kalil is dealing with a groin injury, per Rivera. With Kalil's injury history, it's a situation to monitor.