Tom Cable adjusting QB rotation

NAPA, Calif. -- Kyle Boller will remain the Oakland Raiders' primary backup this week while newly acquired Colt Brennan is expected to finally make his debut.

With Bruce Gradkowski nursing a lingering sore groin and Charlie Frye out after undergoing wrist surgery Wednesday, coach Tom Cable is still adjusting his quarterback rotation for Saturday's preseason game at Chicago.

Boller played nearly three quarters in Oakland's 17-7 win over Dallas last week after replacing starter Jason Campbell early in the second quarter. The former Cal star, who was buried on the depth chart when he signed with the Raiders in April, directed two fourth-quarter scoring drives against the Cowboys.