South Africa carry a 1.68-point cushion over New Zealand into Saturday's inaugural Rugby's Greatest Rivalry Test at Ellis Park, with the world number one ranking at stake from the first whistle.

The All Blacks last held top spot in September and can reclaim it with a win of any margin in Johannesburg. A victory by more than 15 points would give them a 1.82-point lead heading into the following week's Cape Town Test.

For the Springboks, a win inside 15 points is worth 0.83 rating points, pushing them to 94.79. A bonus-score victory — by more than 15 — adds 1.25 points to take them to 95.21. A draw costs them 0.17 points. Neither side risks dropping out of the top two regardless of the result.

Current World Rugby rankings: 1. South Africa 93.96, 2. New Zealand 92.28, 3. Ireland 88.08, 4. France 87.43, 5. England 85.68, 6. Scotland 84.78, 7. Argentina 83.13, 8. Australia 82.67, 9. Fiji 78.00, 10. Wales 76.38.