Her decision to enter the marathon might raise quite a few eyebrows in the long-distance fraternity, especially since she was forced to withdraw from the Olympic Marathon in Rio due to a stress fracture in her left foot.

Van Zyl admits her decision was sort of on the spur of the moment.

'The original plan was that I would compete in the Soweto 21 km or 10 km, but that changed after the SPAR 10 km race in Johannesburg, when I raced without any pain. The fact that I was able to dip under 35 minutes and win showed that I am in better form than I thought,' she says.

'After a short discussion with me, Lindsey Perry, my coach, decided I should do the marathon. The fact that the Soweto Marathon course is quite hilly was a factor in our decision because it means Sunday won't be a fast race.

'At this stage I am not as fast as I was before the Olympic Games, but I have got a good endurance base and I am able to sustain a high tempo running uphill. Mentally, I am ready to run a good race, but it has to be seen whether I am physically up to it.

'In the buildup to the Soweto Marathon Lindsey and I did things slightly different from what we did for Rio. I ran less kilometres in training and continued doing cross-training in the swimming pool and on my bicycle. It is sort of an experiment. If it pays off, it may be the way I will always prepare for a marathon.'

In spite of being able to boast a best marathon time of 2:31:36, Van Zyl claims never to have enjoyed running a marathon.

'In almost every marathon I have run I have had some bad luck, so I have not really got any fond memories competing over 42 kilometres.'

In the 2011 Soweto Marathon Van Zyl fell at the start of the race and was injured, but she continued racing up to the 38 km marker. As she was in tremendous pain by that time, she decided to get a lift in a taxi to the finish.

'I am taking no money with me, which means that I won't have the temptation to get into a taxi. I will be forced to finish what I started, no matter what happens en route.'
Van Zyl says she is aiming to run a time of about two hours and 40 minutes, which she hopes will be good enough for a top-three finish.

Perry, however, is confident she can win.

'We are going to run according to a plan and are gambling that there is not going to be a very strong field, which will mean that Irvette won't have to race too hard to win. But, ultimately, we don't know who else is going to line up. It will be a mistake to underestimate the athletes from Zimbabwe, Kenya and Ethiopia,' says Perry.