The suburban quiet around St Andrew's School for Girls in Senderwood, Johannesburg, has been disrupted by the arrival of hundreds of cars.
They have been parked on every grass verge in the vicinity.
The school's smart new indoor pool facility is packed with swimmers and their parents, who are shuffling for space on the cold concrete steps as condensation rises from the heated pool and steams up the wall of glass at one end of the building.
Children, ranging in age from nine to 13, are in the pool swimming warm-up lengths. Tonight is the opening night of the Gauteng junior swimming championships and the competitors are getting ready for the breaststroke and relay races.
There is a constant stream of movement. Children are picking their way down from the stands and heading for the marshalling area, which is in a white tent outside in the cool night air. There they wait on plastic chairs in tracksuits or in the popular dark-coloured parkas that reach below the knees, hoods pulled over their swimming caps. They file into the building when it is time to race.
Various whistles signal their move to the starting blocks and then the hooter gets them on their way. The noise is deafening. The racers' parents, coaches and teammates are shouting encouragement. Some coaches have a special whistle or a "yup" they use to help their swimmers pace themselves. For the people sitting close to the whistling coaches, the sound is ear-splitting.
At the end of the race, hundreds of heads turn towards the clock that records the times of the racers. Timing is a serious business. There are three timekeepers with stopwatches plus an electronic timing device per lane. There are also officials making sure that swimmers touch the wall correctly – it must be two hands for breaststroke – and execute the strokes properly. Mistakes result in disqualifications and there are quite a few of them, especially after the relay races.
Wet children head back to the stands to their parents and coaches, where they will be met with words of encouragement and much discussion about times. These boys and girls – most of whom probably train for at least an hour a day, four or five days a week – are learning from a young age what it takes to be a Chad le Clos or a Natalie du Toit.
And so are their parents, as they stretch their stiff limbs and make their way back to their cars in the dark. They will be back tomorrow, well before 8am, jostling once again for a seat on the stands.