Northwestern quarterback Dan Persa suffered a left (non-throwing) shoulder injury late in the second quarter against Nebraska and his return in the second half is questionable. Persa initially suffered the injury at about the eight-minute mark of the second quarter, when he was scrambling out of the pocket and landed hard on his left shoulder after the tackle. Persa re-injured it later in the quarter when he slid after a 10-yard run. Backup Trevor Siemian took over for Persa to start the third quarter and will alternate with Kain Colter.