When she turned 30 last year, Brown, an account director for public relations agency Euan Barty Associates, decided she needed some serious goals. 'Hence the running,' she says. 'Hong Kong is such a social place, which is partly why I got into exercise. It's a way to survive in Hong Kong and not gain loads of weight. But losing weight isn't inspiring. It's running a marathon that is inspiring and if a by-product of that is that I lose weight so much the better.'

She began serious training in the new year after indulgent Christmas celebrations. Twice a week, she gets up at 6.30am to run 12km, and goes to the 'hamster wheel' at the gym two days a week. 'I should have started earlier than I did. I had planned to do two to three months of training, but now I've accepted that finishing will be an achievement,' she says. 'It is temporary insanity. I'm not a trained runner. I've come late to this and I'm not particularly stylish or skilful, but I am quite bloody minded.'

Chasing a time under two-and-a-half hours, Brown knows she can keep to six minutes per kilometre over 10km, but can she keep it up for the full 21km? 'I suspect not,' she says.

Two weeks before the big day, however, the training and healthy diet are paying off, and she's beginning to feel it just might be possible. 'I started to feel excited and less terrified,' she says.

But then disaster strikes. An afternoon spent hiking with friends brings back an old knee injury. Her doctor refers her to a physiotherapist.

'Because I've been doing a lot of running, netball and hiking, my muscles have become very short and I'm not stretching enough to compensate,' she says. 'Over time this builds up. Actually it's not a problem with my knees, but with my tendons, which have overstretched between the lower and upper leg muscles.'

It's a common ailment in athletes. Cross-training with swimming or yoga and a supplement of glucosamine sulfate are good preventative measures, says her physio. In the short term, Brown is embarking on an intensive week of deep tissue massage.

'I feel much better,' she says. 'Over the weekend I hoped they were going to say I couldn't do it, because I was in so much pain and I was scared I would damage myself if I pushed myself to the limit. But both the doctor and the physio say it's OK, so I'm quietly confident again.'

Now she's looking forward to the after-party. 'A large, boozy brunch, and possibly some foot reflexology ... I can't wait for Sunday afternoon.'

And she isn't the only one. Among the thousands of other 'fun run' competitors striving for that elusive finishing line are 40 elite international runners from 20 countries. In the men's category, Hong Kong Marathon Best Performer Belaye Wolashe from Ethiopia is returning to try to beat the record he set in 1998 of 2:13:09, while in the women's category, there is defending champion Sun Wei-wei of China, who ran a time of 2:38:55.

Starting on Nathan Road, the marathon route takes in the Cheung Tsing tunnel, the Lantau Link, the Ting Kau Bridge, through the Western Harbour tunnel, finishing with a home run along Connaught Road Central into Golden Bauhinia Square.

It's a tough race, but with more than 21 times the number of participants who took part in the first Hong Kong Marathon, it's grown to be a major event in the world's marathon calendar.