Famed Chinese tennis star Li Na formally announces her retirement due to knee injuries at a press conference in Beijing on September 21, 2014. During her 15-year career, Li won two Grand Slam titles, making her the first-ever Asian to do so, along with seven other Women's Tennis Association (WTA) titles. Photo: Cui Meng/GT 

An emotional Li pauses while announcing her retirement at the press conference. Photo: Cui Meng/GT  

Photo: Cui Meng/GT

Photo: Cui Meng/GT