Newton did not throw in team drills during either practice.
"You could tell he was rusty,'' coach Ron Rivera said Thursday. "A couple late [balls] on the decisions he made. When he was throwing the ball, he was throwing the ball well, so we're not concerned about that.
"Now it's just a matter of him working himself back into shape where he can go out and take normal reps instead of us having to make sure we monitor him.''
Newton, who also didn't play in last week's preseason opener against Houston, had surgery in March to repair a partially torn rotator cuff.
He threw the first five days of training camp, but then was pulled from the second half of a July 30 practice when team trainer Ryan Vermillion noticed fatigue and soreness.
Newton then went 14 days with limited throwing and no participation in team drills until he threw some in the red zone on the last day of the Wofford College portion of training camp.
Rivera has said consistently that the goal is to have Newton ready for the Sept. 10 opener at San Francisco, not the preseason.
Rivera also has said he'd be OK with it if Newton didn't play in any of the four preseason games.