Yao Ming quits NBA

He played only five games for the Rockets last season before being sidelined on November 10 when he injured his ankle during the first quarter of Houston's 98-91 loss to the Washington Wizards.

Neither the Rockets nor the NBA were immediately available for comment on Friday.

Yao had cast doubt on his return to the NBA last month when he admitted to the possibility he may not play again because of his ongoing injury problems.

"I don't know if I would join some champion team in the future," the China Daily quoted him as saying when asked about leaving a new-look Rockets team. "I don't even know if I can play again."

However, Yao said the prospect of playing in front of his baby daughter Amy gave him extra motivation to continue his injury-plagued career in the NBA.

"I wish she could watch me play and even win a championship," he added. "Not only see through video highlights how her dad played. She is definitely a big motivation for me to continue, although my foot still needs lots of treatment.

"Walking or jogging is okay ... but I need to get 80 percent of my strength back to play. I have got only about 30 percent at most now."

Yao's five-year contract with the Rockets, valued at $76 million, expired on June 30, with the threat of a lockout also looming.

The 30-year-old has triggered NBA-mania in China since being selected first overall by Houston in the 2002 draft but has been cursed by injury in the United States.

Yao insisted, however, it would be hard to leave the Rockets because of injury or a trade away.

"I have spent the best 10 years of my life playing and living (in Houston)," said the towering All-Star who has averaged 19.0 points and 9.2 rebounds in his NBA career. "That makes it much harder to bid farewell."