ORCHARD PARK, N.Y. (AP) - Buffalo Bills coach Chan Gailey says running back Fred Jackson has been diagnosed with a concussion and has been ruled out from playing against Miami on Thursday.

Gailey made the announcement Monday, a day after Jackson was hurt in a 37-31 loss at New England.

Gailey said tests confirmed Jackson had a concussion after the player wasn't feeling well on the flight home.

Jackson was hurt in the final minute after taking a blow to head while being tackled by linebacker Brandon Spikes.

Jackson's absence means co-starter C.J. Spiller will handle most of the duties while being backed up by Tashard Choice.

The Bills (3-6) have lost five of six and face a short week in preparing to host their AFC East rival Dolphins (4-5).