The Dragon, The Odds(1979)

Original title: Zhuang ju zai yu Niu gan yan

Mo is a gifted student in one of the village's dozens upon dozens of kung-fu schools. But when the master's away, he leaves the place in the hands of his best student Kang. But Kang rules with a cruel, iron fist. Little does anyone know, however, Kang is really the pupil of his Masters' old nemesis Ken Mo Fung 'The Golden Tiger'. Fung has instructed Kang to discredit the school publicly, then kill his Master by poisoning his tea.