NFL Network's Ian Rapoport reports Smith-Schuster "was diagnosed with bruised ribs," according to sources, and is "considered day-today after undergoing all tests and receiving negative results (negatice is good.)"
Smith-Schuster left Sunday's game in the third quarter, though it wasn't clear when exactly the injury occurred.
The five-year veteran recorded three receptions on four targets for 25 yards.
The Steelers were already lacking at wide receiver prior to Smith-Schuster's injury as Diontae Johnson, who had previously served as the team's top receiving option, experienced a knee injury during the final play of Pittsburgh's Week 2 loss to the Las Vegas Raiders and was inactive for Week 3.
The Steelers also dealt with multiple injuries on their offensive line as right tackle Chukwuma Okorafor was helped off the field after experiencing an apparent injury following a false start and later ruled out to be evaluated for a concussion.
Center Kendrick Green was also evaluated for a knee injury.
Smith-Schuster re-signed with the Steelers in March, acknowledging that a return to the Steel City outweighed offers from the Kansas City Chiefs and AFC North rival Baltimore Ravens.
The Steelers dropped to a 1-2 record through their first three 2021 regular season games with Sunday's loss.