Noting that Edwards was still "pretty sore," coach Dick Jauron said the decision on the quarterback won't be made until gametime. Edwards walked with a slight limp as he watched practice from behind the line of scrimmage.
Edwards tried to play through the injury before being sidelined after the first half of a 10-3 loss to San Francisco on Sunday.
Losman took over and went 11-of-17 for 93 yards, but failed to generate a touchdown as Buffalo came away with three points on three trips inside the 49ers 20 in the second half. Losman lost his job twice to Edwards last season and hasn't started since a 36-14 loss at Jacksonville on Nov. 25, 2007.
The Bills (6-6) have lost five of six and dropped to the fringes of the AFC playoff race as they prepare to play division rival Miami (7-5) at Toronto's Rogers Centre.