Chiefs safety Eric Berry left Sunday's game in the first half with a knee injury, and he didn't return in Kansas City's 41-7 loss to Buffalo.
Chiefs coach Todd Haley said afterward that he didn't yet know the extent of Berry's injury.
But there was concern inside the locker room that the injury could be serious. Berry was tended to earlier in the contest before returning; a few minutes later, the second-year safety was helped off the field.