The following script is from "Li Na" which aired on Jan. 25, 2015. Lesley Stahl is the correspondent. Andy Court, Aarthi Rajaraman and Sarah Fitzpatrick, producers.
It's not unusual for tennis stars to have been groomed from an early age by hard-driving parents. Andre Agassi had his father Mike. Martina Hingis, her mother Melanie. Chinese champion Li Na, who became one of the highest-paid and most-watched female athletes in the world, had a "tennis parent" too. Hers was her country's state-run sports system.
One of tennis' big "grand slam" tournaments, the Australian Open, is underway this week, but without Li Na. After she won last year, she hung up her racquet...leaving the sport after a remarkable career. Remarkable not just because she won two Grand Slams, but because she stood up to the Chinese authorities to win some freedom.
When Li Na reached the finals of the French Open in 2011, 116 million people were watching her back home in China. They were hoping she would make history and become the first Chinese citizen ever to win a Grand Slam tennis tournament. And with this point, she did.
Li Na: I was lying on the ground and the-- hand was in the face. And then I saw (hits mic) wow, blue sky. And I try to cry, but I cannot because so exciting.
It was the crowning achievement of her career up to that point. But she had barely lowered the trophy when she was accused of being ungrateful by failing to properly thank her country for making the victory possible.
Lesley Stahl: One headline called it, "China's Victory."
Li Na: [laughs]
Lesley Stahl: They felt that the country had put so much money and effort into training you. That it was their victory. And you just didn't see it that way.
Li Na: I just thought I was fulfilling my dream.
As she told us in both Chinese and English, she felt it was her victory - as an individual, not as part of a collective. By then Li Na had been questioning the Chinese mindset and standing up to the authorities for years.
Lesley Stahl: You looked to me anyway to be incredibly brave. You challenged the way things were. You were just a little girl, you know. You were just one person.
Li Na: Because I had a goal. I didn't care about the obstacles. I was just heading towards my goal.
She inherited the goal from her father, who had enrolled her in China's sports system at an early age, hoping she would follow in his footsteps and play badminton. She wasn't very good, and a coach suggested she try tennis.
Lesley Stahl: Did your parents even know what tennis was--
Li Na: No.
Lesley Stahl: No?
Li Na: I remember my parents used to call it fuzzy ball.
Lesley Stahl: They didn't even call it tennis.
Li Na: Because back then not many people in China knew about tennis.
By the time she was eight, she was practicing six days a week on these courts in the provincial city of Wuhan. Li Na lived with other players in a Spartan, state-run sports school. That's her on the upper right with the short-cropped hair.
Lesley Stahl: You look like a little boy.
Li Na: Yeah.
Lesley Stahl: Did that bother you?
Li Na: No.
What did bother her was the constant stream of criticism from her childhood coach, Yu Liqiao, seen here grabbing her arm.
Li Na: The way she speak, everyone think she pretty angry, you know. Yeah. So I was like scared.
Lesley Stahl: She was always making you feel you weren't good enough.
Li Na: Yeah. Push me a little bit.
Lesley Stahl: You hated her?
Li Na: Yes. (laugh)
The coach's brutal method was hardly unusual in the Chinese sports system, which was modeled on the Soviet Union's. To this day, China operates a vast network of sports academies that have been criticized for over-training their young athletes, causing psychological stress, and providing inadequate educations.
At 15, Li Na became the youngest person ever to win the National League Singles Finals, but she was lonely and depressed. Her father had died and her mother had fallen deeply in debt.
The one bright spot in her life was a romance with a fellow player on the provincial tennis team, her mixed doubles partner and future husband... Jiang Shaan, aka Dennis.
Lesley Stahl: Did you have to keep it secret in the beginning?
Dennis: No secret for everyone. I think-- maybe only the coaches.
Li Na: Yeah, yeah. (laugh) Only the coaches.
Lesley Stahl: So you did have to keep it a secret from the coach?
Dennis: No, I think that the coach didn't ask it and we didn't answer--
But as time went on, Li Na started feeling bullied by the sports system. During this ceremony in 2001, the official who placed the medal around her neck, slapped her, after she came in third. A few months later, Li Na quit...walked away from tennis altogether. But the tennis authorities begged her to come back, so a year-and-half later she returned and her career took off.
At the 2008 Olympics in Beijing, she upset Venus Williams in the quarter-finals and the crowd went wild.
[Crowd chanting: Li Na ... Li Na...Li Na...Li Na]
She was popular: fans liked her. She wasn't like other typically stoic Chinese athletes. When she lost a big match, you knew it hurt. And she also had a firecracker temper.
In the Olympic semifinals in Beijing she got so angry with her home-country fans, who were shouting encouragement and advice during the match, that she told them to...
[Li Na: Shut up.]
... shut up.
Lesley Stahl: Your childhood made you an angry person?
Li Na: It's not against someone. It's angry about myself because I think I didn't doing good enough.
Lesley Stahl: Because of the echo of the coach in your head and you were kind of beating up on yourself a lot?
Li Na: Yeah. Maybe. Because pretty deep, you know, so it's now--
Lesley Stahl: Scar tissue.
Li Na: Yeah, it's not easy to forget or take off.
Another cause of her anger was that she was competing against Western players who had their own personal coaches and trainers, while she did not.
She felt the government-run system was holding her back. When she complained about this publicly, the head of China's tennis program denounced "the shortcomings of her morals."
Lesley Stahl: You were having difficulty with the system. Not just then -- repeatedly all through this period?
Li Na: Well, I think maybe this was sort of a catalyst for me getting my own team.
She got her own team and was allowed to keep a much larger share of her winnings after the 2008 Olympics. Zhang Bendou, a Chinese tennis writer, says it was a stunning development in Chinese sports.
Zhang Bendou: After 2008 Olympic Games, we have four or five Chinese players, all get more freedom. They can have their own coach, decide their own schedule, but you have to pay your own coach, yeah, and your flight tickets.
Lesley Stahl: But it was seen as a big - I don't know...
Zhang Bendou: It's a big change.
The change put a lot of pressure on Li Na's husband Dennis, who at times, also served as her coach and punching bag.
[Li Na: If you don't want to watch you should just get out of here...you don't need to put on such a stinky face. Is the way I'm playing embarrassing you?
Dennis: I just want to talk to you about...
Li Na: Get lost!]
And in her post-game interviews, Dennis became the butt of her jokes.
[Li Na at Australian Open: Because I didn't have a good evening last night, my husband sleep like... (snore sound)...like this you know.]
Li Na: You know, sometimes I just make the joke.
Lesley Stahl: Did you take it as a joke?
Dennis: [pauses] I don't want to answer that question. (laughter)
During one very difficult period, Dennis left her and Li Na was devastated. They reconciled, and have been inseparable ever since even making TV commercials together.
The extent of her popularity in Asia is hard to overstate. Li Na has more than 20 million followers on China's social media. TIME magazine named her one of the 100 most influential people in the world, and Forbes named her the second highest paid female athlete. If she hadn't fought for more freedom, she would have had to have given 65 percent of her income to the state. Last year, she made an estimated income of $24 million, and she very publicly thanked her agent....
[Li Na: "Max, agent, make me rich, thanks a lot."]
Advertisers see her as a way into the lucrative Chinese market. Her sponsors include Mercedes Benz, Rolex, and Nike.
Her ad campaigns are aimed at Chinese youth, who are attracted to Li Na's feistiness and courage.
Zhang Bendou: I think that young people love her because not only she can win the champions, but also she dare to say "no" to the system, she dare to get out of the system.
After her victory at the French Open in 2011, she fell into an awful slump. She hired Argentinian coach Carlos Rodriguez to get her back on track, and he told her she needed to strike at the source of her anger. So Li Na met with her old nemesis, coach Yu, and told her how her coaching methods had hurt her.
Lesley Stahl: So, was there a release for you in being able to tell her and looking her in the eye?
Li Na: Well, after that, this burden was gone.
Lesley Stahl: Carlos knew what to do.
Li Na: Yeah, he is a very good coach. A very good psychologist.
Her improved attitude paid off at last year's Australian Open when she won her second Grand Slam and became no. 2 in the world. In her victory speech, she thanked Dennis - and brought down the house.
[Li Na: Thanks for him give up everything just traveling with me. Thanks a lot, you're a nice guy. And ... and also you're so lucky - find me.]
The system wanted to take credit for the victory. When she returned home, coach Yu was sent to greet her with a hug for the cameras. Li Na looked happier when she was slapped!
Evidence of Li Na's influence can be found in the rising number of private tennis academies that have opened up around Beijing - with sophisticated training techniques. A new generation of young women want to be the next Li Na.
No one calls it "fuzzy ball" any more!
But shortly after her Australian victory last year, she stunned the tennis world, announcing her retirement. At 32, after multiple surgeries, her tired knees were giving out and so she decided to say goodbye.
She left the game with tears, and some regrets. She even went out of her way to thank the sports system and her former coaches. She told us she planned to live in China, start a tennis academy here, and raise a family with Dennis.
Lesley Stahl: You would like to have children?
Li Na: Yeah. I would love to have at least two.
Lesley Stahl: You don't want to make any announcements on 60 Minutes do you?
Dennis: No, no, no, no.
Lesley Stahl: No, no, no.
Li Na: No. Not yet. (laughter)
Lesley Stahl: Not yet. OK. All right.
But last week at the Australian Open, she had an emotional secret to share with the crowd.
[Li Na: Me and Dennis we are so exciting...our first child will be out in the summer.
Announcer in stadium: Li Na!]
After all her dramas and her courageous fight to control her own career, Li Na says she's at peace, even with the stern and demanding sports system that got her here, the "tennis parent" of her youth.
[Crowd chanting: Li Na!]