Liu Xiang's return to competition is on hold because of lingering problems with the Chinese high hurdler's injured foot, his coach said Tuesday.

The 2004 Olympic gold medalist has already been ruled out of defending his world championship title in August, although he has resumed light training after surgery on his right foot in December in Houston.

"We feel satisfied about Liu's recovery and the medical check revealed that his tendon is getting better but it's not enough yet. He still needs time before coming back to competition," Liu's longtime coach Sun Haiping was quoted as saying by the official Xinhua News Agency.

The world championships are in August in Berlin followed by the Shanghai Golden Grand Prix event in September.

Liu's injury kept him from defending his 110-meter hurdles title at last summer's Beijing Games.

"There's really no need to rush. It is immature for him to run in competitions at this moment. We can count Liu in when he is fully ready. If he injures his leg again, it will certainly end his career once and for all," Sun told a news conference in Shanghai.

Liu set a world record of 12.88 seconds for the event in 2005, but Cuba's Dayron Robles lowered the mark to 12.87 last year and also won gold at the Beijing Olympics.