Guice played for LSU from 2015 till 2017 before entering the draft. He started his freshman and sophomore season as a backup to Leonard Fournette. He started his first career game in place of an injured Fournette during the team’s second game of the season and ran for 155 yards and a touchdown on 19 carries. Against the Arkansas Razorbacks on November 12, Guice rushed for 252 yards, which was the second-most in a game in school history.
