Yao Ming's hopes of playing at the 2011 FIBA Asian Championship remain in doubt, said Liu Wei, the national team captain and Yao's former teammate with the Shanghai Sharks.

"Nothing is certain right now. He didn't tell me whether he will play at the championship," said Liu, who teamed with Yao to claim the Sharks' only Chinese Basketball Association (CBA) crown in 2002.

Although Yao is still trying to overcome a left ankle fracture which has sidelined him since last December, the CBA placed him on the national team's roster for summer training this month.

The CBA hopes injury-plagued Yao can help the country fight for the only direct berth to next year's London Olympics at the Asian Championship in September, despite the fact that 30-year-old Yao just took off his protective boot a month ago.

Liu is cautiously optimistic after meeting Yao in Shanghai after the giant returned from Houston on April 13.

"He will stay in Shanghai for a while and then go back to the States for an injury check. Nobody knows if he will be able to play until the results come out," Liu told China Daily while appearing at a clinic organized in Beijing by his sponsor, Nike, to instruct a media basketball team.

After a humiliating 70-52 final loss to Iran at the 2009 Asian Championship on home court, China is keen to win the title back from its archrival.

Captain Liu feels confident about the squad's prospects at the Wuhan, Hubei province, tournament while stressing "chemistry within the team" is crucial.

"We must secure the title at the Asian Championship this time, not only paving the way to London, but winning back respect in Asia," said 31-year-old Liu, who is tuning up for the event with a personal trainer in Shanghai now.