Chinese player Li Na, a two-time Grand Slam   champion, announced her retirement on Sept 21 because of long-term knee injuries. Although it was a hard decision, Li said she had no regrets  . "I don't feel sorry about retiring, because I've tried my best," said the 32-year-old. Becoming professional at the age of 17, Li has set many milestones   for Chinese tennis. She was the first Chinese player to win a WTA title and the first to break into the top 20. Li won the 2011 French Open title and became the first Asian player to ever win a Slam. By winning this year's Australian Open, she became the first Asian player with two Slams. As excellent as her tennis abilities are, Li's sense of humor is _ too. She often jokes about life with her husband in interviews, changing them into funny comedy shows. Her speech at the Australia Open in January is just the best example. During her 15-year professional career, Li has helped the improvement of tennis in China. Earlier this month, Chinese another player Peng Shuai, 28, made the semifinals of the US Open. Last week, a new tennis match started in Li's hometown of Wuhan. "I've seen changes happening in front of my eyes, young girls picking up tennis rackets, setting goals ... and believing in themselves," Li said in an online post. Li is more than a sports superstar. As WTA chief executive   Stacey Allaster said, she is "a pioneer who opened doors to tennis for hundreds of millions of people throughout China and Asia." Li said she planned to take care of my family and then to open a tennis school in China after her retirement. Her official retirement ceremony   will be on Sept 30. When did Li Na become the first Asian player with two Slams?
In 2011. In 2012. In 2013. In 2014.