Four mixed-martial-arts matches enliven this urban exploitation flick, which ultimately is defeated by its clashing materials. Authentic locations and careful attention to detail help evoke several New York boroughs in all their gritty vitality, but the screenplay about a hunky street vendor turned underground fighter (Channing Tatum of Stop-Loss) is sloppy and false. Without a concrete time frame the hero's rise seems impossibly quick, and the bruises and cuts he sustains are minor and too artfully applied—presumably so that his romance with a troubled nightclub waitress (Zulay Henao) can advance as fast as his career. Terrence Howard struggles to add substance to an underwritten role as Tatum's manager, to little effect. Dito Montiel (A Guide to Recognizing Your Saints) directed. PG-13, 105 min.