Cheung Po Tsai was a navy colonel of the Qing dynasty and a former pirate. "Cheung Po Tsai" literally means "Cheung Po the Kid". He was known to the Portuguese Navy as Quan Apon Chay during the Battle of the Tiger's Mouth.

The Battle of the Tiger's Mouth was a series of engagements between a Portuguese flotilla stationed in Macau, and the Red Flag Fleet of the Chinese pirate Ching Shih, led by her second-in-command, Cheung Po Tsai - known to the Portuguese as Cam Pau Sai or Quan Apon Chay. Between September 1809 and January 1810, the Red Flag Fleet suffered several defeats at the hands of the Portuguese fleet led by José Pinto Alcoforado e Sousa, within the Humen Strait - known to the Portuguese as the Boca do Tigre - until finally surrendering formally in February 1810. After her fleet surrendered, Ching Shih surrendered herself to the Qing government in exchange for a general pardon, putting an end to her career of piracy.