Two days after announcing the end of her momentous tennis career in an open letter to friends and fans, Li Na entered her farewell news conference with the appearance of somebody who had been crying.

It didn't take long for the two-time Grand Slam champion to shed tears, again, as she explained her decision to retire in the wake of a fourth knee operation.

"I feel this is the best time for me to retire. I don't feel sorry or have any regrets about retiring," she told a packed news conference Sunday at the National Tennis Centre in Beijing. "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."

"I'm very satisfied with my tennis career," added the 32-year-old Li, who won the French Open in 2011 to become Asia's first Grand Slam titlist. She won her second major in January, finally claiming the Australian Open title 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 knee injury.

"After the surgery in July, I tried very hard to recover, hoping I can make it to participate in tennis matches in China especially the Wuhan Tennis Open which is the first ever big tennis match in my hometown, Li said. "However, this is my fourth big surgery, and with my age and physical state, it is hard for me.

"This is a tough decision to make for me, even harder than playing the Grand Slam matches. But I think this is about the right time to say goodbye to everyone, because my body doesn't allow me to participate in any high-level tennis matches."

Li set a host of milestones, including being the first Chinese player to win a WTA title, the first to break into the top 20 and the first player from Asia to win a tennis major.

The WTA, which runs women's tennis, described Li as a trailblazer in the game and the continent. She wants to ensure that what she's achieved is just the start for tennis in China.

"What I really want to do now is try to set up a tennis school of my own and do basic things to help build up the base for Chinese tennis," Li said. "Like a pyramid, I believe only with a solid base, Chinese tennis can have a better future."