God of Gamblers (movie, 1989)

Chow Yun-Fat plays Ko Chun, an extremely talented and well known gambler. On the eve of a big confrontation with a famous Singaporean gambler, Ko walks into a trap set by Knife, an avid but a so-so gambler (Andy Lau), meant for an Indian servant. Struck on the head, Ko suffers from amnesia and regresses to a child-like state. Knife takes care of Ko and begins to exploit Ko's gambling talents.