South Africa's grip on the world No.1 ranking will be tested in Buenos Aires on Saturday when they face Argentina in a one-off Test that carries significant consequences beyond the result itself.

Rassie Erasmus' side currently hold a rating of 93.96 points, 1.68 clear of New Zealand. But defeat to the Pumas would cost them at least two rating points — three if the margin exceeds 15 points — and hand top spot back to the All Blacks. South Africa dethroned New Zealand last September and are closing in on an unbroken year at the summit, but Argentina's home record against the Springboks makes this fixture a genuine threat.

Three of Argentina's four wins over South Africa since 1993 have come on home soil, most recently the 29-28 victory in Santiago del Estero in 2024. Elrigh Louw, who featured in that defeat, acknowledged the lessons learned. "Argentina is a real quality side, and we learned our lessons from the last time we played here," Louw said. "We lost that game in 2024, so the focus for me is on doing my job, and to ensure that we match their physicality."

Forward battle looms large

Prop Zach Porthen, set to earn his sixth cap, is relishing the challenge of Argentina's formidable scrum. "Personally, the biggest place I want to get my foot in the ground is at scrum time," Porthen said. "Being a tighthead prop, I'm just hoping I can try and enforce a bit there and keep improving day by day." The former Junior Springbok captain made his debut late last year and will play his first match in Argentina.

Louw, meanwhile, returns after a serious knee injury kept him sidelined for an extended period last year. "It was quite a big injury and it was devastating at the time," he said. "But the motivation to be back in the Springbok squad was more than enough for me to continue working hard and play rugby to the best of my ability."

A Springbok victory would maintain their 1.68-point cushion and extend their dominance in recent meetings — 13 wins in the last 15 encounters. But the stakes at Estadio José Amalfitani extend beyond rankings points. Another defeat in South America would raise questions about South Africa's ability to close out tight contests away from home, particularly as the Rugby Championship cycle builds towards the 2027 World Cup.