Williams suffered a thigh bruise during Sunday's win over the Lions, Ian Rapoport of NFL Network reports.
The Bears appear to believe Williams' injury is minor and won't impede his ability to suit up Week 5 against the Raiders, but with David Montgomery (knee) also dealing with an injury, the team's backfield picture suddenly is muddy. Montgomery still is undergoing medical evaluations, and early reports are optimistic he's avoided a torn ACL, but the severity of his injury isn't yet clear. Behind Williams and Montgomery stands only rookie Khalil Herbert, while Tarik Cohen (knee) will need to remain on the PUP list until at least Week 7.