South Africa's grip on No. 1 isn't under serious threat, but it's not ironclad either: a loss to Scotland by more than 15 points, combined with a New Zealand win over Italy, would hand the All Blacks top spot. Beyond that Bok-specific scenario, the weekend's Nations Championship and Nations Cup fixtures could produce meaningful reshuffling across the top 10 — Scotland could climb to a historic high of third or fourth with a win, while Japan could crack the top 10 for the first time in nearly two years. Wales are also in reach of a top-10 return. The full permutations matrix from World Rugby is worth scanning if you want to know exactly what combination of results affects any given side.