When Paula Radcliffe crossed the line to win the ING New York Marathon seven days ago, her time of 2hr 23min 9sec was almost eight minutes slower than her world record, yet it could prove to be one of the most significant performances of her career.

In 40 weeks’ time, Radcliffe will face her defining moment. The Olympic Games marathon in Beijing takes place in the early hours of Sunday, August 17, probably to a backdrop of some of the toughest conditions she has ever run in: heat, humidity, and a wave of pollution.

Chinese Olympic officials, mindful of the fact that the eyes of the world will be on them, are examining every possible way of cutting down on the immense dust cloud that descends upon the city, but the atmosphere is likely to be like nothing Radcliffe has experienced before. As an asthma sufferer, it might not present the most pleasant of occasions.

But as Radcliffe spends the next fortnight planning her route towards Beijing - it could include competing in both the world cross-country championships in Edinburgh in March and the Flora London Marathon in April - preparing to run her slowest ever race over the 26.2mile distance may be the essential element if she is to achieve the victory that would crown her wonderful career.

In this modern age of marathon running, championship events no longer produce fast times, and in the next nine months Radcliffe must contemplate that. Arguably, she has never looked so awkward in a marathon than at the Olympics in Athens in 2004, when she failed to break away from the leading pack, the major trait of all her marathon victories. Conditions in the Greek capital were difficult, but Beijing is expected to be considerably worse. Yet two of Radcliffe’s main rivals in the countdown to 2008, former world record-holder Catherine Ndereba of Kenya, and China’s Zhou Chunxiu, proved at this summer’s world championships in Osaka that they have what is needed.

Zhou is the fastest marathon runner in the world this year, leading the rankings with 2:20.38 from her victory in London in April. In Osaka she was second in 2:30.45 as Ndereba, who has a best of 2:18.47, triumphed in the stifling morning heat in temperatures that touched 30C in 2:30.37. These are times which are not even among the top 50 this year. Last month, the relatively-un-known Chinese athlete Chen Rong won the Beijing International Marathon in 2:27.05.

But can renowned front-run-ner Radcliffe, whose world record of 2:15.25 has stood for more than four years, and who has run four of the fastest times in history, win a marathon at least 12 minutes slower than she has in the past?

Radcliffe knows the run-in to 2004 did not work, when she ended the marathon sitting on a pavement three miles from the finish in tears after stopping. She says: “It’s nice to have the reassurance that I don’t have to do another marathon before Beijing.

“Hopefully, I have ticked all the boxes I need to to get to the Olympics. I could say that the important thing is to save energy and stay safe over the next few months but that’s what I did in 2004, when I missed out on a lot of races that I would like to have run, but that didn’t work out either. Athens simply showed there are absolutely no guarantees.”

With a population of 11m, dust and ozone levels in Beijing rise to a rate that is two to three times higher than is recommended by the World Health Organisation, particles amassing from power plants and factories, while the city’s infamous traffic jams have reduced speeds to an average of 12mph.

UK Athletics (UKA), the sport’s national governing body, is using Osaka as a major guide to what Beijing might bring. But they are preparing for the worst possible conditions, even though tests carried out on athletes at last year’s world junior championships did not show a significant impact from the atmosphere.

Dr Bruce Hamilton, UKA’s chief medical officer, said: “I do not know if you can say it will be better or worse than the Olympics in Athens, but it will be tough. The heat will be a bit different. Osaka was very oppressive, but it has given us some indication of how people tolerate the heat. It was good to have the championships in that part of the world to give us a lot of experience.”

Radcliffe says that her worst asthma attack came at a cinema in Loughborough, but UKA are running a series of tests on all of their athletes in the build-up to Beijing. Hamilton says: “There has been a lot of hype and concern about the pollution levels in Beijing. That is something we have taken on board quite seriously, firstly by recognising those people who are asthmatic so that we can prepare them. Getting that medication right for an asthmatic is a key thing for us leading into Beijing.

“The reality is that we plan for a worst-case scenario. If it does not happen, it does not happen.

For a lot of the time in Athens, it was not as hot as we had anticipated, the pollution was not as bad, and we are hoping in the back of our minds that it will not be as bad as what we are preparing for in Beijing, but we are preparing for the worst. “We are looking at appropriate supplementation to minimise the issues around allergies. We produced a booklet for Osaka which was a preliminary run for next year, and it has a comprehensive guide to hydration strategies leading into and during the event. One of the other areas is: when do you go into Beijing? Do you go in very late or very early?”

But the elements hold no fears for Radcliffe. “I’m not frightened of racing in Beijing,” she says. “The heat, the humidity and the pollution is something that you simply have to adapt to, and it is something that I have to have under control. But it will be tough for everyone. If you are in good shape and you acclimatise properly, then you will run well.”

Even if you do not have to run as quickly as normal.