Chinese Olympics swimming champion and world record holder Sun Yang apologised on Monday after a Porsche SUV he was driving without a license collided with a bus in eastern China's Hangzhou city.
Sun was not injured in the incident which happened on Sunday afternoon, the state-run Xinhua news agency reported.
The swimmer took to his Sina Weibo microblog to say sorry.
"I should have been a role model as an athlete and a public figure but I failed my responsibility," Sun wrote on the popular Twitter-like platform.
"I am deeply sorry for what I have done and will reflect on my behaviour. Because I have been focusing on training and competition, I had only a hazy knowledge of the law, which led to my mistake," he added.
"After this incident, I will strengthened my knowledge and study of the law to prevent such a thing from happening again. I hope that everyone will take this as a warning and give me an opportunity to correct my mistake."
Xinhua reported that Sun was driving a Porsche Cayenne SUV he said he had borrowed from a relative when a bus hit him from behind.
Hangzhou police then discovered he could not produce a driver's license, the report added.
"After looking into the system, we did not find any record of his license. Sun admitted he did not have one," an unnamed Hangzhou police officer was quoted as saying.
Sun could be fined up to 2,000 yuan ($330) and may face up to 15 days detention, the report added.
Sun shot to fame after becoming the first Chinese man to win an Olympic swimming gold medal, transforming him into one of the country's most sought-after sportsmen.
While Sun, like other Olympic champions, is a popular sports figure in China and will probably be forgiven by the public for the crash, this is not the first time he has been in trouble.
In February he was suspended from all commercial activities for breaching a "series of team rules". According to Xinhua, Sun had fallen out with his long-time coach Zhu Zhigen who felt the swimmer had too many commercial obligations.