Stills was originally listed as questionable after being limited in practice this week. But he was downgraded when the Saints made their trip to Atlanta.
It makes sense for the Saints to play it safe with Stills, who suffered at least two setbacks with the quad strain this summer.
The Saints still have plenty of depth at the receiver position -- especially after re-signing veteran Robert Meachem on Wednesday. They also have receivers Marques Colston, Brandin Cooks, Joe Morgan and Nick Toon on the active roster, not to mention receiving tight end Jimmy Graham.