Cox stepped in for the injured starters Tramaine Brock (toe) and Chris Culliver (concussion) Sunday and collected three tackles and an interception in the win over Dallas. The 27-year-old cornerback was immediately thrown into the fire Sunday, but responded well in the wake of several 49er injuries. The interception was just the second of his career and first as a 49er. It is unknown whether Brock (toe) and Culliver (concussion) will be ready to go before next week's home opener against Chicago, but Cox showed that he is more than capable if the team calls on him again.