Asomugha was taken to the locker room to be evaluated for head and neck injuries in the second quarter and did not return.
Asomugha appeared to hit the back of his head on Williams' knee, then hit the ground very hard. He was motionless on the field for a few moments before getting up and walking off under his own power.
Backup Philadelphia safety Colt Anderson injured his left knee covering a punt and also did not return.
The Associated Press contributed to this report.