It has always been destined to be a victory parade, the moment when the Chinese celebrate their staging of the Olympics with the nation’s favourite sportsman winning their only gold medal on the track. There may be stacks of successes in the more traditional Chinese sports, such as table tennis and diving, gymnastics and weight-lifting, which should propel the country to the top of the medal table for the first time. However, what the host nation has craved has been to adorn the Bird’s Nest stadium with Liu Xiang winning the 110m hurdles, to demonstrate how the Chinese can excel in an event for which they do not seem physically suited.

If Sydney had Cathy Freeman in the final of the women’s 400m as the centrepiece of the 2000 Games, then Beijing has been focused to an even more suffocating extent on Liu Xiang. Everywhere in Beijing, his face has been beaming down from advertising hoardings.

When he broke the world record in Lausanne two years ago, there was a 20-minute item on the national news. In public, he is mobbed wherever he goes and he has been forced to drive around in a car with darkened windows to escape the persistent attention of obsessive fans. When a competitor was chosen to run the first leg of the torch relay at Tiananmen Square in Beijing in March, there was only one possible candidate.

His Olympic victory, which a country of 1.3 billion people insists must take place next month, could well still happen. Liu has the pedigree. He was, after all, gold medal-list four years ago in Athens, equalling the world record of Britain’s Colin Jackson and demonstrating that he can produce his best in the most fraught of conditions. Liu thus became China’s first male Olympic athletics champion in history.

Liu said of his performance: “[It] changes the opinion that Asian countries don’t get good results in sprint races. I want to prove to all the world that Asians can run very fast. I am a Chinese and considering the physiology of the Chinese people, it is something unbelievable.”

He also became the first athlete of nonAfrican descent to go under 13 seconds for the distance. Liu followed up his victory in Greece with a silver medal at the 2005 world championships and then began to dominate the event as he got older and more experienced, setting his world record the following year.

He was the 2007 world outdoors and 2008 world indoors champion and a few months ago seemed the unquestioned favourite to add another Olympic crown this year. Perhaps, as he celebrates his 25th birthday today, he can still be comforted by being regarded as the favourite for the Olympic title, but he is no longer the unquestioned favourite. Victory has now become far from assured.

When Liu won his speciality, to rapturous applause, in the Goodwill Games in the Bird’s Nest stadium in May, a test event for the Olympics, he bounced off the track to say, predictably, that “the venue is up to international standards and the track was okay for me, not too soft and not too hard”.

Everyone was relieved. Liu’s endorsement was the one that counted for the authorities and the confidence in his own prowess heartened his supporters.

Then things began to go awry. Knowing that he doesn’t have the necessary opposition in Asia to sharpen his form and fitness, two races were arranged in June in the United States. Liu was forced to pull out of the Reebok Grand Prix in New York at the beginning of June with a sore hamstring, a perennial hazard in an event where competitors have to stretch their lower bodies at speed to get over the barriers. However, he did enter the Steve Prefontaine Classic in Eugene, Oregon, insisting that he had recovered from his injury. Feng Shuyong, the national team coach, who was accompanying Liu, was adamant: “It was a very big consideration and we certainly didn’t want to take any risk.”

However, Liu was disqualified from the event for a false start, his third in as many races. His personal coach, Sun Haiping, explained that “it was a relatively small accident. He was just too eager to run well”, saying that the mistake had nothing to do with the recent hamstring strain. He added: “Over the next month, we will focus on his start.” The group then hurried back to Beijing to restart training while planning to get a couple of domestic races in China before the Games.

However, when Liu lines up for his heats in the Olympics, it does not seem likely that he will have taken part in any high-class outdoor race this year.

After the setback in the United States, worse was to come. On June 12, Dayron Robles, more than three years younger than Liu and running in the outstanding tradition of Cuban hurdlers, shaved one hundredth of a second off Liu’s world record in Ostrava in the Czech Republic.

His time was 12.87sec, which Liu greeted, with his customary measured courtesy, by saying: “I had expected it to happen some-day, as Robles is very capable of running under 12.90sec. He has been my main rival over the past two years. Neither of us will show mercy at the Olympics, so let’s wait and see what happens then."

Liu’s coach simply regarded the loss of the world record as motivation for his charge to work harder. However, this was not the end of the bad news for the Chinese. In the US Olympic Trials last weekend, David Oliver confirmed his prominence this year, running 12.89sec in the semi-final and 12.95sec in the final, even if both times were aided by a wind above the limit for record purposes. Oliver qualified as the No 1 string for the US.

If Liu is to retain his Olympic title, he is likely to have a much sterner fight on his hands than was expected even six weeks ago. Defeat would be a disaster for him, for China and for his many admirers.

He is widely appreciated for his technical proficiency. Colin Jackson says of the man who took away his world record: “It would be different if someone like Roger Kingdom [the 1984 and 1988 Olympic champion] had broken it. He was a real bull, but was not what one would call the smoothest hurdler in the world. Liu is completely different. He’s a nice fluent, silky hurdler.”

Alan Pascoe, the former British international who won both Commonwealth and European hurdles titles, says: “He is very smooth but also aggressive with his lead arm, getting him low across the hurdles. He has the build – he is 6ft 2in – and leg length to maximise the drive off the hurdles, and this helps his stride pattern. But he is also quick on the ground. Colin Jackson [who is 5ft 11in] could have been two inches taller [to help him stretch over the barriers].”

Pascoe added: “Colin was so fast on the ground – look at the way he so often used to make up distance at the finish, and he was also technically brilliant. So is this Chinese lad, but now he is under real pressure from the Cuban.”

Pascoe, the chairman of Fast Track, the sports marketing agency, believes that Liu Xiang is still one of the relatively unknown names in international athletics, pointing out that although he is a hero in China, he is “relatively unknown to the man in the street in Britain”.

However, this could change with another victory in Beijing, which would make him the third high hurdler, after the Americans Lee Calhoun and Roger Kingdom, to retain the Olympic title. His lack of global status is partly the result of his upbringing in China, where he has been honed discreetly in the system and has run less frequently than he might have done in Grand Prix meetings.

Born in Shanghai, the only child of a lorry driver and a pastry cook, he was brought up with the aid of an extended family, including a grandmother who used to cook him braised pork in a brown sauce.

They were reluctant to allow him to become part of the Chinese conveyor belt of sporting talent, but despite their opposition, he enrolled, aged 12, in a junior sports school and won a national age-group title in the high jump. However, it was forecast that despite his early growth spurt, he would not be tall enough to become a world-class jumper.

He was rescued by Sun Haiping, already a renowned hurdles coach, and changed events.

Although Sun described Liu’s technique as “terrible” in the early days, they worked together on the fluency of the movement and his suppleness so that he could skim over the barriers with little loss of momentum. He made his debut internationally at the 2000 world junior championships, where he finished fourth.

A year later, by now 18, he won the World Student Games title. His father recounts that when Liu returned home from that victory, he rushed to the hospital where his beloved grandmother was dying of cancer. “He gently propped her up, tenderly hung the gold medal round her neck, holding it so that the medal would not become too heavy for her.”

The Chinese public have appreciated such stories of Liu’s humanity. As Feng Shuyong says: “Girls like him, old ladies like him, even men.”

However, Feng recognises that Liu’s victory in Athens four years ago, which put him on a lonely pedestal, has had its drawbacks, which have been exacerbated by China hosting the Games. Feng says: “He’s a young man and wants to do many things, but he can’t. I feel very sorry for him.”

Liu himself says: “Being famous is sometimes a good thing, but sometimes not. I prefer not to be famous. My situation has changed. I have money now but I can’t shop.” Not even for his favourite casual clothes - “all the sports clothes I have are from sponsors” - because he gets mobbed whenever he appears in public.

Speaking of the Olympics, he says: “I will try my best, but I still have to live after this period. I think that when I retire it will be better."

First he has his date next month with his American rivals and particularly with the Cuban, Robles.

He says of the encounter in the Bird’s Nest stadium: “I hope it will be the second birthplace of my dreams.” All China, and Liu himself, are praying that it will not be a nightmare.