The Substitute 3: Winner Takes All (1999) on Netflix

Plot summary

In a Kosovo prison, mercenary Karl Thomasson watches his friend Macy take a beating; before Macy dies he hands Karl a medal for his daughter, Nicole Stewart, an English professor at Eastern Atlantic University on Long Island. Karl escapes with an Albanian girl held there and kills their two guards. Three months later he visits Nicole, who is reluctant to take the medal because her father's military service kept him away from her. Football players at the college pressure her to pass them unfairly, and Karl steps in. When she is attacked and hospitalized on her way home, Karl poses as a substitute teacher, with help from his friends Ed Lincoln and Rahmel, to find out who is responsible.