Gailey provided the update Monday, a day after both were hurt in the third quarter of a 23-17 loss to Tennessee.
He gave Chandler an "outside chance" of playing after the team's top tight end hurt his left ankle while being gang-tackled and stripped of the ball.
Gailey calls the injury to Williams' right knee not as severe as initially expected. He gave him a "real shot" of returning Dec. 11, when Buffalo hosts Miami.
Buffalo (5-7) has lost five straight.
Gailey expects starting safety George Wilson to miss his fourth straight game with a neck injury.