Scalzo, a 6-foot, 180-pounder from Fort Lauderdale, Florida, had surgery last fall as a high school senior for a torn anterior cruciate ligament in the knee.
Kentucky coach Mark Stoops said Tuesday that Scalzo was hurt while trying to plant and make a cut during Saturday's scrimmage. He will have surgery next week.
The coach added that he was disappointed for Scalzo because he had "worked extremely hard" to recover from the surgery.
Scalzo is one of three players featured in the current season of the Netflix documentary series "QB1: Beyond the Lights," which follows their senior seasons of high school.