Li Na, China's 1st Grand Slam singles champion, retires from tennis tour due to injuries

Li Na, a two-time Grand Slam champion from China who took tennis in Asia to a new level, has announced her retirement.

The 32-year-old Li posted the news on her microblog Friday, citing a recurring knee problem.

Li won the 2011 French Open, becoming the first player from China to win a Grand Slam singles title, and clinched the Australian Open title in January in her third trip to the final at Melbourne Park.

She only entered seven tournaments after that, and hasn't played since a third-round defeat at Wimbledon. She withdrew from three tournaments in August, including the U.S. Open, citing a right knee injury.