ESPN first reported the development.
After getting a full practice in on Wednesday, Smith-Schuster was downgraded to limited on Thursday. NFL Network's Aditi Kinkhabwala reported that JuJu left practice early.
The Steelers' top receiver has missed the past three games since suffering a concussion and knee injury in Week 11. Smith-Schuster was cleared from concussion protocol weeks ago, but the knee issue continues to nag.
The Steelers will once again likely have to manage without their top wideout. Pittsburgh, on the strength of its defense, has won all three games sans Smith-Schuster. Assuming JuJu sits again, Devlin Hodges will lean on rising rookie Diontae Johnson and James Washington as his primary receivers against a very good Bills pass defense.