One time Olympic champion hurdler Liu Xiang is unlikely to compete at this year's IAAF World Championships in Beijing.

The 2004 Athens Games 110-meter hurdles gold medalist withdrew from both the 2008 Beijing and 2012 London Games, due to injuries and hasn't returned to the track for two-and-a-half years.

Liu, 31, who has endured a long recovery from a right Achilles tendon injury that sidelined him from racing in London, appeared at a 200-day countdown ceremony for the Beijing Worlds at the Bird's Nest on Tuesday as one of seven athlete ambassadors for the event.

Asked whether he could still make it to race at the Worlds, he said: "I think the possibility is pretty slim. I might be able to take part in the event in another role (not as an athlete)".

His remarks came two days after Wang Dawei, deputy director of the State Administrative Center of Track and Field, said at the 2014 CCTV Sports Personality awards ceremony that Liu "is still training in hopes of competing at the Worlds".

Even though Liu has physically recovered sufficiently to return to the training track current results (in trial races) haven't been up to the qualification mark for the World Championships, Wang said.

"A lot of young athletes have emerged as high-level contenders in the world. Some have already been able to reach the top eight or win medals in their respective events. I hope the public could pay more attention to them and the coming championships," said Liu, who won gold in the 110m hurdles at the 2007 Worlds in Osaka, Japan.

Others named as event ambassadors include Olympic race walking gold medalist Chen Ding, men's sprinter Zhang Peimeng and national long jump record holder Li Jinzhe.

The World Championships take place at the Bird's Nest from August 22 to 30. The ticketing plan was released on Tuesday with the price for a whole day session ranging from 50 yuan ($7.9) to 1,000 yuan.