The race to claim a top-four spot looks set to go right down to the wire
There are 14 matches this week which could impact the IRB World Rankings, with the only certainty being that New Zealand, who have occupied top spot since 16 November 2009, will not improve their rating with victory over Italy in Rome.
For a second successive week, Australia are the key side in the battle for the top four positions.
The Wallabies head for Twickenham to take on an England side keen to make up lost ground after surrendering fourth spot to Australia's conquerors France.
The IRB World Rankings on 3 December will be used to band the 12 directly qualified teams from Rugby World Cup 2011 for the pool allocation draw for England 2015.
The race to claim one of these top four spots - and therefore avoid the big guns until the quarter-final stages of RWC 2015 - looks set to go right down to the wire.
For Australia, France and England this weekend, it comes down to this: win and they will be in the top four when the rankings are updated on Monday, November 19, regardless of other results.
The next three weekends are crucial for England as they face three sides currently in the top four in Australia, South Africa and New Zealand.
England and Australia have shared the spoils in their matches over the past 10 years with seven wins apiece, though the men in white won their most recent encounter, at Twickenham in 2010.
Another home victory would restore England to the top four, but it won't be France that makes way provided they beat Argentina as home wins in London and Lille would push Australia from third to fifth in the world.
This would equal Australia's lowest position since the IRB World Rankings were introduced in October 2003, a placing the Wallabies have not occupied since early 2008.
There is similar jockeying for position in the next band for the pool allocation draw - those sides ranked five to eight - with Ireland looking precarious and unable to do anything about their rating this weekend as an Ireland XV take on Fiji in a non-cap match in Limerick.
South Africa, second in the rankings after beating Ireland 16-12 last weekend to benefit from Australia's loss, could lose to Scotland and still remain in the top three, but the reward for the Scots would be eighth place, shifting Ireland down into what would be band three for the draw.
Historically, South Africa are comfortably ahead of Scotland in the overall head-to-head, but the Scots ran out 21-17 winners when the sides last met, at Murrayfield, two years ago.
A repeat will be key for Andy Robinson's men if they are to avoid a pool with two higher ranked opponents for the second Rugby World Cup in succession, having drawn Argentina and England in 2011 and missed out on the quarter-finals for the first time.
Argentina, who climbed above Ireland into seventh after beating Wales 26-12 in Cardiff, are also a key factor in this weekend's ranking permutations.
If Los Pumas beat France in Lille they would climb above a Welsh side regardless of their result against Samoa at the Millennium Stadium on Friday.
The news for Argentina could get even better though, as a top four spot is not beyond them, depending on their margin of victory and the outcome at Twickenham.
France could retain a top four spot despite a defeat, although they would be relying on Australia to rediscover the winning feeling at Twickenham to avoid England climbing above them again.
Les Bleus may be on a roll after their convincing win over Australia, but Argentina have proved something of a bogey team in the past for them.
The French have lost six of their past 10 matches against the Pumas, although the stats in that time read 3-3 for matches in France. The two sides met twice in June with honours shared in Argentina.
Although Wales were surprised by Argentina last week, the two sides look steady in the second band of seeds at six and seven; if Wales beat Samoa and Argentina lose to France, the status quo remains.
If Samoa can cause another upset in Cardiff over their Welsh hosts though, Wales along with Ireland are in danger of slipping out of the second band of seeds.
Samoa's date with Wales - a side they have beaten twice in RWC history in Cardiff - means that Tonga take their place in the IRB International Rugby Series in Colwyn Bay and face USA on Saturday, the same day that Canada tackle Russia.
A win for the Eagles could lift them up two places to 15th, above two sides who meet in Tbilisi - Georgia and Japan.
The Brave Blossoms climbed above Georgia last weekend after beating Romania in Bucharest, but defeat in their first ever meeting on Georgian soil will see the hosts on the rise again.
Spain, who like Georgia kick off their bid to qualify for RWC 2015 in February, play twice this week - against Zimbabwe and Namibia in a Tri-Nations series in Windhoek - and will hope to reduce the deficit to Romania above them.
Their Iberian rivals Portugal also have more gains in sight, having already climbed three places after beating Uruguay in Montevideo last weekend, when they tackle Chile, the side now directly below them in 25th.