Sorry if this has been posted already but i was trying to find info on why Li/Sun and spilt and found this..
Chinese Olympic Tennis Doubles Champions Split
Athens Olympic doubles champions Li Ting and Sun Tiantian will be separated and paired up with other players for the qualifying rounds of the Beijing Olympics.
Sun Jinfang, Director of the Tennis Administrative Centre of General Administration of Sport, on Thursday announced the decision was made due to Li and Sun's under-par fitness levels, despite their gold medals at the Athens Olympiad in 2004.
Sun said Li Ting and Sun Tiantian have tried re-partnering with Sun Shengnan and Ji Chunmei respectively. The final line-up for the Olympic Games will be determined according to the WTA ranking and form of individual players by mid-2007.
The director also revealed Li Na and Peng Shuai may compete in the doubles event. He also confirmed that Australian Open and Wimbledon Open doubles champions Zheng Jie and Yan Zi would definitely compete in the 2008 Olympics.