Thorson was carted off the field with a right knee injury.
The junior quarterback is out for the game, and the injury appeared to be serious.
The Wildcats have lost their star quarterback.
Northwestern quarterback Clayton Thorson was carted off the field late in the first quarter of the Music City Bowl with what appeared to be a severe knee injury.
Thorson suffered the injury to his right knee after catching a 24-yard pass from backup running back Shane Larkin. He appeared to have hyperextended it while taking on contact from Kentucky linebacker Jordan Jones.
Thorson was replaced by longtime backup quarterback Matt Alviti, a fifth-year senior. Alviti has taken snaps in 14 games during his career, completing 11 of 19 passes for 119 yards and one touchdown.
WGN Radio sideline reporter Adam Hoge noted that Thorson was undergoing x-rays on his right leg shortly after being carted inside.
Thorson was able to move the knee while he was being evaluated, per ESPN sideline reporter Olivia Harlan.
Thorson, a junior, recently announced he would be returning next year for his senior season, so Pat Fitzgerald and the Wildcats will still have more time with one of the best quarterbacks in school history.
At the half, Northwestern leads Kentucky 17-7.
More to come.