Li Na retires: Persistent knee injuries forces two-time grand slam winner to end career

Chinese star won 2011 French Open and 2014 Australian Open

China's Li Na poses with the trophy after her victory against Slovakia's Dominika Cibulkova during the women's singles final at the 2014 Australian Open tennis tournament in Melbourne (SAEED KHAN/AFP/Getty Images)

Two-time grand slam winner Li Na has announced her retirement from the sport after struggling to overcome knee problems.

Reports emerged on Thursday that the 32-year-old Chinese, who won the 2011 French Open and 2014 Australian Open singles titles, had chosen to hang up her racquet.

And the world number six confirmed on Friday in a lengthy statement that fitness troubles meant she could no longer play at the level required.

The statement read: "Representing China on the tennis court was an extraordinary privilege and a true honour.

"Having the unique opportunity to effectively bring more attention to the sport of tennis in China and all over Asia is something I will cherish forever. But in sport, just like in life, all great things must come to an end.

"Most people in the tennis world know that my career has been marked by my troubled right knee. The black brace I wear over it when I step on the court has become my tennis birth mark. And while the brace completes my tennis look, the knee problems have at times overtaken my life.

"After four knee surgeries and hundreds of shots injected into my knee weekly to alleviate swelling and pain, my body is begging me to stop the pounding. As hard as I tried to get back to being 100 per cent, my body kept telling me that, at 32, I will not be able to compete at the top level ever again. The sport is just too competitive, too good, to not be 100 per cent.

"Winning a Grand Slam title this year and achieving a ranking of world number two is the way I would like to leave competitive tennis. As hard as it's been to come to this decision, I am at peace with it.

"I've succeeded on the global stage in a sport that a few years ago was in its infancy in China. What I've accomplished for myself is beyond my wildest dreams. What I accomplished for my country is one of my most proud achievements."

Li has not played since losing in the third round at Wimbledon in June to Czech player Barbora Zahlavova Strycova, sitting out the US Open.

Her success in becoming Asia's first grand slam singles champion has made her a national sporting hero in China, with Time Magazine naming her among its 100 most influential people in the world in 2013, featuring her as the cover star.

Her off-court earnings have been vast, outweighing on-court income, with Li behind only Maria Sharapova in this year's Forbes list of highest paid female athletes. She was estimated to have earned around £14.5million in total for the 12 months to June 2014.

PA