Whitner, who missed the second half of Buffalo's Monday night loss to Cleveland, is nursing a right shoulder separated against the Jets on Nov. 2. Greer, meanwhile, hurt his right knee in the Browns game.
Buffalo's secondary might be even further depleted if Whitner's replacement, Bryan Scott, can't play. Scott is questionable because of a left knee injury sustained against the Browns.
Rookie Leodis McKelvin will likely start in place of Greer, while George Wilson would start at strong safety if Scott is unable to go.
Though listed as questionable, starting receiver Josh Reed will likely play for the first time since spraining an ankle in the first half against Miami on Oct. 26. Reed practiced all week after missing the last three games.
The Bills (5-5) also placed reserve linebacker Marcus Buggs on injured reserve Friday after he sustained a high ankle sprain against the Browns. To take his place on the 53-man roster, Buffalo promoted linebacker Dustin Fox from the practice squad.