Stanford will have to ignite its struggling offense and break a three-game losing streak Saturday without its starting quarterback.

K.J. Costello has been ruled out against Oregon State, and redshirt sophomore Davis Mills will be making his second career start when the Cardinal plays at the Beavers’ Reser Stadium Saturday (4:10 p.m., Pac-12 Network).

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Former Santa Clara University head coach takes over Mitty’s girls volleyball program Though Stanford doesn’t disclose injuries, Costello hurt the thumb on his throwing hand in the opening series of last Saturday’s 21-6 loss to Oregon. He finished the game but was ineffective, going just 16 of 30 for 120 yards and an interception.

Mills played the second half of the season opener against Northwestern, and then started in Week 2 at USC, after Costello suffered an apparent head injury. Mills is 32-for-55 for 352 yards, a touchdown and an interception this season.

Stanford (1-3, 0-2) has scored just five offensive touchdowns and is 1-3 for the first time since 2007. The Cardinal haswon nine straight against Oregon State (1-2, 0-0).