For the first time since the IRB World Rankings were introduced in late 2003, this November will see all of the top 20 sides in action, starting this weekend when Australia tackle England at Twickenham and Wales face New Zealand in Cardiff.
New Zealand arrive in Europe on the back of a 32-19 victory over the Wallabies in their Bledisloe Cup encounter in Tokyo last weekend and as a result even an emphatic loss at the Millennium Stadium will not alter their position of second.
Wales, though, have not beaten New Zealand since a 13-8 victory at the Arms Park on 19 December 1953, the All Blacks having won 20 Tests in a row, the most recent a 29-9 success at the Millennium Stadium last year.
The closest Wales have come to victory in this time are two one-point losses in 2004 and 1978, but if they can break this losing streak they will climb a minimum of two places to sixth in the IRB World Rankings.
However they could climb as high as fourth, providing that they were to beat New Zealand by more than 15 points and England condemn Australia to a seventh defeat of 2009 by a similar margin at Twickenham.
Lowest position for Australia?
In this instance, New Zealand would see their ranking fall by over two points - leaving them four behind number one side South Africa - and Australia drop two places to equal their lowest ever position of fifth.
Australia's slide would see Ireland rise to third for the first time in three years and Wales to fourth, not to mention leaving the Wallabies sitting less than three tenths above England in sixth.
England will climb one place in victory, regardless of the winning margin, with a positive result for Wales also resulting in two place falls for France and Argentina to seventh and eighth respectively.
Wales could actually climb a place to seventh in the IRB World Rankings even in defeat, with a third Australian victory in four visits to Twickenham leading to a one place fall for England to eighth.
New Zealand can close to within a point of the Springboks with another emphatic victory - six of their last seven in Cardiff have all been by a minimum of 20 points - and even a similar win by Australia will still leave them trailing the All Blacks by more than four points.
Key warm-up for Namibia
Portugal, meanwhile, will face a Namibian side eager to secure a confidence boosting victory ahead of crucial Rugby World Cup 2011 qualifiers against Tunisia this month with a place in Pool D awaiting the Africa Cup winner.
The two sides have not met in nearly 12 years since Namibia won 36-19 in Lisbon and the African side will be hoping to remain unbeaten against Portugal with victory over their higher ranked hosts on Saturday.
Portugal, ranked five places and 5.56 points above Namibia, will not improve their position of 20th as even a victory by more than 15 points will still leave them more than a point behind their European rivals Romania.
Namibia will climb a minimum of two places with victory at the Estádio Universitário de Lisboa, but could leapfrog Portugal and end the weekend in their highest ever position of 21st with an emphatic win.
Os Lobos will fall either one or two places in defeat with Uruguay the beneficiaries of any Portugal loss with a return to 20th position in the IRB World Rankings.
European battles continue
There are also four matches in the European Nations Cup, although Bosnia & Herzegovina's visit to Azerbaijan won't impact the ranking as their hosts are not yet a full Member Union of the IRB and therefore not ranked.
The Netherlands welcome Latvia to Amsterdam in one of two Division 2B encounters on Saturday, but given the 24 places and 9.26 points between the sides a victory - regardless of the winning margin - will not alter their position of 36th.
However if Latvia can cause an upset and win their first ENC match of this campaign - while also handing the Dutch their first loss - then they will jump five or six places to 54th and condemn their hosts to a potential seven place slide.
Malta will be looking to complete the double over Sweden, having beaten them 9-6 away last November. If they do manage this, they must win by more than 15 points to improve their ranking of 54th.
In this instance Malta would climb three places to 51st with Sweden plummeting eight places to take over their hosts' former position. Even with a smaller margin of defeat in Paola, Sweden would still slide five places.
The other encounter pits the bottom two sides in the ranking against each other in a Division 3C encounter with Finland travelling to Luxembourg in the knowledge that a victory by more than 15 points will see the sides swap places.
Luxembourg currently sit four points above their visitors and even an emphatic victory will not improve their position of 94th, only inch them slightly closer to Vanuatu above them.
The IRB World Rankings update every Monday at 12:00 UK time.
