Liu Xiang's dream of defending his Olympic title on home soil ended on Monday when he failed to start his first-round heat in the 110 metres hurdles.

Liu, the world champion and the host nation's best hope of an athletics gold medal at the Beijing Olympics, pulled up after a false start and hobbled down the tunnel to leave the Bird's Nest stadium in stunned silence.

He was clearly out of sorts and grimaced in pain as he went down into the blocks.

After a false start, he stumbled forward for a few paces obviously hindered by the injury to his right leg before walking away and leaving a packed Bird's Nest stadium in stunned silence.

"Liu Xiang has two injuries, one to his Achilles and one in his leg. One of the injuries is an old injury," his tearful coach and mentor Sun Haiping told a news conference.

"It's the end of the Achilles tendon in his right foot," he added. "He will be back for sure."

The China athletics team's head coach Feng Shuyong said 25-year-old Liu had sustained the injury in training on Saturday.

"This morning he felt the pain intensify," he said. "Even though he felt the pain he decided to compete in the first heat.

"Liu would not withdraw unless the pain was intolerable and there was no other way out."

Along with basketball player Yao Ming, Liu is China's favourite sportsman and there was a huge weight of expectation on him to repeat his triumph of 2004, when he became his country's first male Olympic champion on the track.

"I just saw him outside and he is very disappointed," Feng added. "We have done everything we can.