Knockout (2011) on Netflix

Plot summary

Matthew Miller is the new kid at his high school and wants a spot on the boxing team. Hector Torres, the school's boxing champion, bullies him, and a scuffle between the two lands Matthew in Principal Lee's office with a week of detention. His mother, Christine, and his stepfather, Jacob, are against his joining the club, and Matthew argues his case at home until they agree. On his first day in the club he is matched to spar with Hector, and a cheap shot after the referee stops the round gets him thrown out. Dan Barnes, the school janitor and a one-time pro boxer, watches the session and offers to train him.