Li Na's link with Nike started when she was just a girl, training at one of the brand's tennis camps. It's a relationship that has lasted nearly two decades -- and the Chinese star is so important to Nike that it named a building at its new China headquarters after her.
The 32-year-old announced her retirement Friday in a long post on social media, saying her knee injuries had become too much to overcome. "My body is begging me to stop the pounding," she wrote.
Ms. Li, a two-time Grand Slam champion, has been an inspiration for her success on court, but also for her humor, sincerity and individuality. Though she started in China's state sports system, she broke away in 2008 to pursue her own training path.
In her retirement letter, she urged fans to work hard for their dreams, using a phrase that sounds odd in English: "Be the bird that sticks out."
Nike took that phrase and built a campaign around it (strangely, the bird reference does not appear in the Chinese-language version of her farewell letter, though it does in English.)
The phrase is a reference to a Chinese expression. As Nike explained in a news release, it "derives from the Chinese proverb, 'The bird that sticks out always gets shot,' a stern reminder to keep in line, follow the rules and be aware of the perils of resisting convention."
Nike added: "Li boldly provided an example of someone who stood for what she believed in. She chose her own path outside of the traditional system and soared to a level of success that few Chinese athletes have reached."
On Weibo, China's Twitter, Nike posted the slogan with an image of Ms. Li inside a cutout of a phoenix spreading its wings. It was forwarded nearly 10,000 times in six hours, with many commenting on Nike's speedy reaction. (It was unclear whether Nike was able to prepare in advance.)
China's young people "really have a strong sense of 'we' but also of 'me,'" said Terry Rhoads, managing director of Shanghai-based sports consultancy Zou Marketing. "This campaign will speak well to the generation of young people who are very individual in thinking about what they want, what they want to achieve."
Mr. Rhoads, who was the China director of sports marketing for Nike from 1994 to 2002, recalled Ms. Li as a teenager, before she got braces: "Her teeth were not all straight, but that didn't stop her from smiling ear-to-ear the whole time," he said. (Occasionally her fiery temper would also come through, he said.)
While Nike said Ms. Li's relationship with Nike started when she was a 15-year-old training in the U.S., Mr. Rhoads said he dated it back even further, to when she was just 12 and taking part in a Nike international tennis camp.
"Some athletes can spend their entire career with one sportswear brand -- the thing about Li Na is she did it from age 12," Mr. Rhoads said. (Ms. Li also has signed endorsement deals with many other brands over the years, from Mercedes to Samsung to China's Yili dairy brand.)
Ms. Li "helped people around the world better understand Chinese people and feel a little better about China, and that's something the Chinese people really love her for," Mr. Rhoads said.
In retirement, Ms. Li has said she wants to start her own tennis academy for young Chinese players, and Mr. Rhoads says that's an opportunity to continue the Nike relationship.