ORCHARD PARK, N.Y. - Buffalo Bills coach Doug Marrone says running back Fred Jackson is not yet ready to return against the Kansas City Chiefs, but he'll see how things progress the rest of this week.

Marrone said Thursday he's not sure if Jackson will be available.

Jackson was limited in practice for a second day in a row on Thursday. The 33-year-old is making his way back from a groin injury he suffered on Oct. 19. Jackson has 239 yards and one touchdown on 55 carries this season.

Rookie receiver Sammy Watkins sat out Thursday after suffering a groin injury in practice Wednesday. Marrone declined to offer details, referring to Watkins' status on the injury report instead.

Buffalo (5-3) is home against Kansas City (5-3) on Sunday.