Pioneering Chinese tennis star Li Na said Sunday she has "no regrets" about her decision to retire over persistent knee injuries, but wiped away tears as she acknowledged she thought long and hard about the decision.

The two-time Grand Slam winner was making her first public remarks since she announced her shock retirement via social media on Friday.

"I'm very satisfied with my tennis career," the 32-year-old Li told a news conference at China's National Tennis Centre, which hosts the China Open later this month.

"I feel this is the best time for me to retire. I don't feel sorry or have any regrets about retiring. When I was making this decision, I asked myself, 'If I retire, will I regret it?'"

"My heart told me I wouldn't, because I've done my best," she said.

The event was an emotional one both for Li and the nearly 200 journalists who attended.

At one point, a Chinese journalist raised his hand to ask a question, but then suddenly went silent before breaking down into tears.

Li responded with her characteristic wit.

"Here, take this," she said, holding out a tissue from her seat at the podium and holding back tears of her own.

Li's announcement comes just seven months after she lifted the Australian Open title, one of her career highlights following her historic French Open win of 2011.

In postings on Facebook and Chinese social media Friday, she wrote that "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".

On Sunday, as she ended a career that has brought her nine titles and introduced tennis to the masses in China, she maintained that she has "done no great thing".

"I want to tell everyone -- because everyone has his or her own dream -- you must keep pursuing your dream," she said.

The next Li Na may arrive "at any moment", she added.

"Just keep an eye out," she said. "The next player will be even better than me."

'Fly alone'

Li became a sporting pioneer in China when she decided to break from the state sports system in 2008 with a group of up and coming players, in a move dubbed by local media "fly alone".

The move meant she was able to choose her own coaches and keep most of her winnings rather than giving them to the government.

But asked Sunday whether she would encourage future generations of Chinese athletes to do the same, she demurred, and focused instead on the positive aspects of her time within the state system.

"I actually don't like the phrase 'fly alone'. It's a term made up by the media," she said. "Personally, I prefer the phrase 'more professional'."

She added that if she had not trained with China's national team, she would not have been able to achieve her current success.

"I really miss the time I was on the national team... training together, living together, I think you can have a lot of friendship," she said.

Li said her post-retirement plans include working to further the development of tennis in China and working with children, including those with disabilities.

A child of her own may also be part of her future plans, the married star suggested.

"Children are one part of life," she said.

Li's news conference coincided with the first day of the Wuhan Open, a new premier-level tournament established on the back of her success.

The $2.4 million event, which will be headlined by Serena Williams and Maria Sharapova, is being held in Li's home city in central China's Hubei province. The tennis trailblazer is expected to meet fans there on Tuesday.

World number four Sharapova led tributes to Li in Wuhan, saying: "It is obviously a very big loss for tennis in general all around the world, and specifically here in China where Li Na has been so influential for so many years."

World number two Simona Halep described Li as a "real champion", while two-time Wimbledon winner Petra Kvitova said China "can be very proud of her".