Chan Sai Kau (Chinese: 陳世九; Cantonese Yale: Chàn Saigáu, born 26 August 1952) is a retired Hong Kong professional football player. He is regarded as one of the best defenders in the 1970s. He played for South China for many years. He then transferred to Happy Valley with teammates Choi York Yee and Fung Chi Ming in 1978-79 season by signing a contract of HKD$5,500 per month. This was a big contract value at the time. He represented Hong Kong to compete in the first Guangdong-Hong Kong Cup in 1978-79. He immigrated to Britain after finishing his career but has now moved back to Hong Kong.