“American Fighter” (**1/2 out of four) was an agreeably done action melodrama about a tough teenager (George Kosturos) who is forced into the treacherous world of underground fighting to save his ailing mom and becomes caught between a greedy and malicious promoter (Tommy Flanagan) and a former fighter (Sean Patrick Flannery) who wants to train him. Routine story covers all the B-movie bases and cliches but is proficiently made with likeable performances making this not a knockout punch but a mild enough jab. Very similar and on par with 1992’s “Gladiator.”