Reggie Bush, who injured his left calf during San Francisco's opener against the Minnesota Vikings, is the only 49ers player on the team's injury report.

Bush left the field during the first quarter and was eventually carted to the locker room. He had an MRI performed on Monday at Stanford and remains week-to-week. The calf strain is not believed to be serious and there was no tear involved.

San Francisco 49ers

Questionable: RB Reggie Bush (calf)

Pittsburgh Steelers

Questionable: CB Cortez Allen (knee), CB Brandon Boykin (groin), LB Ryan Shazier (knee)
Probable: S Will Allen (concussion), QB Landry Jones (concussion), S Mike Mitchell (hip), LB Sean Spence (hamstring)