With just under two months until the Rugby World Cup 2015 Pool Allocation Draw takes place in London, South Africa’s place in what will be the top group of seeds is under threat as they welcome Australia to Loftus Versfeld this weekend.
South Africa, bidding to avoid a third successive defeat in The Rugby Championship, currently sit third in the IRB World Rankings but a loss by more than 15 points on home soil will see them fall two places with England and France the beneficiaries.
This scenario would also see Australia reduce the deficit to New Zealand above them to 4.22 points as even an emphatic victory for the All Blacks on their first visit to Argentina since 2006 would have no impact on their rating.
This is because New Zealand, who have occupied top spot in the IRB World Rankings since 16 November 2009, are seven places and 13.09 rating points above Los Pumas, who drew 16-16 with South Africa in their previous Rugby Championship match on home soil.
New Zealand will not surrender top spot even if they suffer a first ever loss against Argentina, although their cushion could shrink from its current 5.81 rating points to just 1.22 if they lose heavily and Australia run riot in South Africa.
If Argentina can create history at the Estadio Ciudad de La Plata on Saturday then they will climb above Ireland into seventh place in the rankings, although a win by more than 15 points would also lift Los Pumas above Wales and bring them to within a point of a coveted top four ranking.
While defeat could prove costly for South Africa, a victory by more than 15 points will see them climb above Australia into second place, a position they last occupied before their Rugby World Cup 2011 quarter final defeat by the Wallabies.
The penultimate weekend of The Rugby Championship, though, is not the only action that could have an impact on the IRB World Rankings as Paraguay host Bermuda in the latest RWC 2015 qualifying match in the Americas.
Paraguay, who cantered to the South American B Championship title earlier this month, are ranked 10 places higher than Caribbean champions Bermuda, their visitors to Asunción on Saturday.
The South Americans will climb two places to 37th with any margin of victory at Club Universitario de Asuncion and condemn Bermuda to a one place fall, slipping below Senegal to 50th.
On the other hand, if Bermuda win then they will climb to a new high of 40th with Paraguay falling between three and seven places depending on the margin of defeat, either of which will result in their lowest ever ranking.