The Polk County Sheriff's Office says Christopher Michael Campbell pointed the knife at one of the Kathleen High School players during practice Wednesday. No one was injured. Campbell was arrested the next day.
Authorities say the 30-year-old Lakeland man later admitted to the school's athletic director that he took a knife to practice and told players, "Don't try me today."
Campbell has been charged with assault with a deadly weapon without intent to kill and exhibiting a weapon within 1,000 feet of school property.
The sheriff's office didn't know whether Campbell has an attorney.