LONDON -- Chinese hurdler Liu Xiang had undergone a surgery on a torn Achilles tendon of his right foot at the Wellington hospital of London, officials said on Thursday.

Chief official of the Shanghai Sports Bureau told Xinhua that the surgery took 79 minutes and the doctors were optimistic about the results.

Liu will stay in the private hospital for two or three days before ?returns to Shanghai.

The Chinese phenomena stumbled on the first hurdle in the men's 110m hurdle race on Tuesday and was diagnosed as suffering a torn Achilles tendon.

Liu needs at least four weeks to recover, a Chinese doctor said.