The NFL has flexed the Packers/Falcons game out of prime time Dec. 8 (week 14), and will instead air the Panthers/Saints game on Sunday Night Football on NBC.
The Packers/Falcons game moves to 1 p.m. on Fox, where the Panthers and Saints had been scheduled.
The NFL has the option in weeks 11-17 to move games with more playoff implications into prime time. The Saints are only one game ahead of the Panthers in the race for the NFC South crown, and given that the third-place Buccaneers are only 3 and 8, one or the other will almost certainly win that division.
The NFL has to make its flex moves at least 12 days before the weekend in weeks 11-16. Because things could be changing up until the potentially crucial last week, it can make that week 17 move with only 6 days notice.