Pressure is a funny thing. Some athletes feed on it and use it to lift them to a higher plane, but for others it proves to be an unbearable weight that crushes their spirit.

Michael Phelps has no problems with pressure, seemingly able to pull out whatever is necessary to win when all appears lost. Cathy Freeman carried an entire nation to victory in her 400m final in Sydney. That is what makes them champions.

Others aren’t so lucky. Australia’s Tamsyn Lewis promises so much and yet falls apart in big competitions. Greg Norman earned a reputation for imploding when in the lead in the final round of gold tournaments.

Few people, however, would ever experience the sort of pressure that China’s Liu Xiang faced before the heats of the men’s 110m hurdles. Liu is a giant in China, he is the face of global giants Coca-Cola and Nike. He is even bigger than basketball giant Yao Ming, who is much more familar to Westerners.

Liu won the gold medal in Athens in 2004 and set a world record in the process and, in doing so, set in motion the build-up of expectation that has come to suffocate him. Gone is the easy-going, relaxed and carefree athlete who faced the starter in Athens to be replaced by a man who has been forced to become a virtual recluse by his popularity and constant scrutiny.

China had never before won a gold medal in men’s track and field competition at the Olympics. In fact, when Liu won, he claimed it as a victory over the Chinese physiology which was widely believed to be unsuitable for track and field.

Liu continued to excel, picking up both indoor and outdoor world championships and things were on track for a crowning performance at the Beijing games. But then the wheels started to fall off.

False starts and injuries started creeping into the normally flawless Liu’s performances. These started at about the same time that Cuban Dayron Robles started to present a serious challenge.

It has been reported that Chinese government sports officials have told Liu that should he not win in Beijing, all of his past achievements would be meaningless. That seems like a hell of a way to motivate an athlete.

Rumours had been rife in the lead-up to the heats of the hurdles that all was not well with Liu, but it was not until he started his preparations for his heat that it became apparent just what that meant.

Liu’s demeanour let everyone know that he wasn’t comfortable. His facial contortions, grimacing and exaggerated rubbing of his wounded leg set the scene for what was to follow. He carried a limp worthy of Saturday matinee pirate. He gave every impression of a man who wanted to be somewhere else.

A false start saw Liu hobbling before the first hurdle and the effort of stopping apparently was the final straw. He ripped off his numbers and disappeared down the tunnel to the stunned disbelief of 80,000 devoted Chinese fans.

The world will never know how bad the injury was. Cynics would say that it is the perfect cover for a man who was out of form and allowed him and the government to save face under the harsh spotlight of international scrutiny.

We will never know whether it was a mental or physical failure that brought about Liu’s undoing. Whatever the reason, it has robbed not just China, but the world, of an opportunity to see a champion in action - an outcome that no one would have wanted.