Ranked as world number 6 by the Women's Tennis Association (WTA), former French and Australian Open champion, Li Na announced her retirement on Friday morning in Beijing. The decision to retire came as a result of aggravated knee injuries that have haunted her throughout her career.

The 32-year-old announced her retirement after winning the Australian Open just seven months back. The winner of nine WTA singles titles stated that the knee injuries had been a hindrance in her playing to the best of her abilities since long back.

Li Na wrote on her weibo microblog, "As a professional tennis player, it is the best decision for me to leave the field." Talking about her knee injuries, she further added, "for a long time prevented me playing as I had before".

She also wrote, "I've achieved far more than I'd dreamed for, and it's my biggest pride to have won glory for the country."

Li also expressed her wish to launch her own tennis academy. She wrote, "Personally looking forward to opening a new chapter of my life."

Li's popularity shot up after she won her second major title at the Australian Open attaining her career's best ranking of second.

However, besides the knee injuries keeping her from playing to the best of her potential, she even had to deal with other challenges like her coach, Carlos Rodriguez ending their partnership in July.

Li underwent a fourth surgery on her right knee after her loss at Wimbledon following three surgeries on her right knee from 2008-2009.

She wrote, "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," 

Three years ago, Li won a Grand Slam tournament at the French Open and she was the first Chinese player and Asian to do so. This flared up a tennis boom in Asia.

With annual earnings of $23.6 million, Li is second in a 2014 Forbes listing of highest-paid athletes.