The second-year running back is unlikely to play against the Patriots on Sunday, a source told NFL Network Insider Ian Rapoport.
Conner practiced for the first time on Friday, albeit in a limited capacity, since suffering an ankle sprain in Week 13 and was originally listed as questionable. The Steelers downgraded Conner to doubtful on Saturday.
Conner was missed last week in Pittsburgh's loss to the Raiders, when starting running back Jaylen Samuels compiled just 28 rushing yards on 11 attempts, and veteran backup Stevan Ridley added five carries for four yards and a touchdown. Samuels and Ridley are expected to carry the load again versus the Patriots.
Conner has 1,376 total yards and 13 total touchdowns on 253 touches this season.