The 24-year-old fencer was set to compete on Sunday, but hurt his knee during training on Wednesday in Shenzhen.
The Hong Kong fencing team’s head coach, Zheng Zhaokang, said Cheung’s knee was swollen, and he therefore decided to send him home for safety reasons.
Cheung later wrote on Instagram that an MRI scan revealed that he suffered a minor meniscus injury.
He thanked people for their concern.
Cheung won the men’s individual foil event at the Tokyo Games in July.