A 220-pound gym teacher in New York who used to pound through defensive lines as a star college running back, has finally met his match ... a 50-pound first grader.

John Webster, a hulking 27-year-old phys-ed teacher is suing his school after first grader Rodrigo Carpio attacked him. Webster claims the boy fractured his ankle, injured his knee and forced him to visit a shrink to deal with stress.

Webster told the New York Post, "[Rodrigo] looks like an angel, but then, all of a sudden, that halo turns into horns. It’s been a nightmare. It’s embarrassing. It’s humiliating.”