Costello led Stanford to a Week 1 win over Northwestern on Saturday in his 25th career start.
Stanford quarterback K.J. Costello is questionable for the Cardinal's upcoming matchup with USC on Saturday, head coach David Shaw announced.
Costello exited Stanford's Week 1 matchup with Northwestern on Aug. 31 after receiving a hit to the head late in the second quarter. The senior was 16-for-20 for 152 yards before leaving the contest. Junior Davis Mills replaced Costello in Week 1 and is expected to start vs. USC if Costello is unable to play
Stanford will still miss a critical piece against the Trojans even if Costello lines up under center. Offensive tackle Walker Little is out for Saturday, and he will miss "at least six weeks or so," per Fox Sports' Bruce Feldman. Little was named to Sports Illustrated's preseason All-America team on Aug. 16.
Stanford defeated Northwestern 17-7 on Saturday. The Cardinal are seeking their ninth-straight winning season with head coach David Shaw in 2019.