The Detroit Lions could be without Calvin Johnson this weekend.

Lions coach Jim Caldwell said Friday if Johnson's ankle doesn't improve by Sunday, there is a chance he won't play against the Buffalo Bills.

"That possibility always exists," Caldwell said. "Just kind of depends on how one progresses during the course of the week. There are some times that they move forward enough that they won't have any significant setbacks and other times you don't feel that way. You have to wait until the end of the week and react accordingly."

Johnson missed the first two practices of the week but returned Friday, just as he did last week.