French number one Bartoli, ranked 10th in the world, was 4-3 down against Taiwan’s Chang Kai-Chen when she retired due to a stomach illness.
Lucky loser Chang will play Taiwan's Su-Wei Hsieh for a place in the quarter-finals.
There was another surprise as sixth seed Monica Niculescu went out at the first hurdle, the Romanian losing 7-5 6-2 to Mathilde Johansson of France.
Johansson will play Zheng Saisai of China after she beat American Julia Cohen 7-6(1) 7-5.
China’s second seed Zheng Jie was a break up in the first set when Taiwan’s Chan Yung-Jan retired injured. Jie, now the top remaining seed, will face Britain's in-form teenager Laura Robson in the second round.
"I practiced with her when I arrived in Guangzhou, that was the first time I played with her," Zheng said of Robson. "She played well in the US Open and won a silver medal in mixed doubles at the Olympics. I think she'll be a future star."
Other seeds to progress were number three Sorana Cirstea – also of Romania – who beat Hu Yueyue of China 6-2 7-5, while fourth-seeded Pole Urszula Radwanska beat Hungary’s Melinda Czink 7-6(1) 6-2.
Cirstea faces China's Yingying Duan after she beat Thailand's Luksika Khumkhum 6-2 6-1, while Radwanska is up against Luxembourg's Mandy Minella.
Eighth seed Alize Cornet of France took the first set 6-3 before Alexandra Panova of Russia retired injured. Cornet plays Belarusian Olga Govortsova after she beat Zarina Diyas of Kazakhstan 7-5 6-2.
In matches between unseeded players, Nudnida Luangnam of Thailand surprised Australian Jarmila Gajdosova 6-7(5) 6-4 6-2, while Su-WeiHsieh of Taiwan beat Nina Bratchikova of Russia 7-5 6-3.
Luangnam has to content with Chinese star Shuai Peng next, with Hsieh up against compatriot Chang.