Thielen (hamstring) has been ruled out for Sunday's game against the Giants, Mike Kaye of The Charlotte Observer reports.
Thielen returned to practice Oct. 23 but didn't participate at all this week. While the Panthers haven't said anything about a setback, it's possible that's what happened. In any case, the team will need to place Thielen back on the active roster next week if he's going to play again this season rather than staying on injured reserve for the rest of the year.