49ers CBs Dontae Johnson, Perrish Cox prove to be valuable replacements

As a fourth-round pick with nothing more than a fill-in performance on his NFL resume, San Francisco 49ers rookie Dontae Johnson expects Jay Cutler and the Chicago Bears to throw at him early and often Sunday night.

Johnson passed his first test last week when starting cornerbacks Tramaine Brock and Chris Culliver and rookie nickel cornerback Jimmie Ward left San Francisco's 28-17 season-opening win at Dallas with injuries.

Brock injured a toe, Culliver sustained a concussion and Ward had a head injury. Johnson and journeyman Perrish Cox entered in relief and smothered Tony Romo and the Cowboys' prolific passing game.

Brock and Culliver remain sidelined, so Johnson and Cox will likely be called up against the Bears this week.