Yao Ming played just five games in the final two seasons but said he was happy to have walked away from the game while he still could.

"I survived it. That's what I'm proud of," he added when asked if he was frustrated that the injuries may have robbed him of a career that was entering its prime.

Yao said the toughest opponent he faced in the NBA was Shaquille O'Neal, the former LA Lakers center who was one of the most successful and recognizable players in the sport.

"He was not only big from outside, he's big from the inside. Mentally he just wants to try and eat you on court.

"That's another reason I'm proud I survived."