Duel of Fists (Chinese: 拳擊; Quan Ji or Kuen gik) is a 1971 Hong Kong martial arts film directed by Chang Cheh and starring David Chiang and Ti Lung.

Filmed on location in Bangkok, the story concerns a Hong Kong engineer (Chiang) who goes to Thailand to find his long-lost half-brother (Ti Lung), who is a Muay Thai boxer.

Fan Ko, an engineering architect in Hong Kong who is also highly skilled in martial arts, is called to the bedside of his dying father, who reveals that he long ago had an affair with a woman in Thailand, who bore him a son.

So Fan Ko catches a Cathay Pacific flight to Bangkok Airport and is met by a family friend and booked into a room at the Dusit Thani Hotel.

However, at Lumphini Boxing Stadium, the atmosphere is decidedly less festive, as another young boxer has been killed in the ring by the current champion, Cannon, who is backed by the local Triad boss and a crooked fight promoter, Qiang-ren.

Fan Ko, meanwhile, is nosing around at Lumpini stadium, and thinks that a fighter named Miller may be his brother after he sees a large plywood cutout of the boxer and notices the anchor-and-bird tattoo.