Whoever emerges victorious on the penultimate weekend of the 2009 - be it defending champions New Zealand or world champions South Africa - in Hamilton will sit top of the IRB World Rankings.
South Africa currently occupy that position, albeit only now by a mere four hundredths after suffering a first defeat of the year at the hands of Australia, 21-6 in Brisbane - a city they have not won in since the Tri Nations began.
They will be on unchartered territory in Hamilton, the All Blacks never having played a Tri Nations match at Waikato Stadium. The last time New Zealand played in Hamilton was in June 2007, when they overwhelmed the touring Canadians 64-13.
South Africa will be looking to make it a clean sweep of victories over the All Blacks in 2009, having won 28-19 in Bloemfontein and 31-19 in Durban over consecutive weekends in late July and early August.
However New Zealand has not been a happy hunting ground for the Springboks, their narrow 30-28 win in Dunedin last year being only their second - and first since a 13-3 success a decade earlier - in the history of the Tri Nations.
South Africa know that victory in Hamilton on Saturday will not only ensure they remain on top of the IRB World Rankings, but will also secure a first Tri Nations title since the 2004 success under coach Jake White. A draw will also have the same outcome.
Title still up for grabs
The Springboks currently have 17 points going into their final match of the 2009 competition, with New Zealand on eight and Australia a further point adrift following their impressive victory over South Africa last weekend.
Only the All Blacks can deny South Africa the Tri Nations title, although they would need to beat both them and also Australia - at least one of them with a bonus point - and deny South Africa any bonus points.
If South Africa do emerge victorious then they could turn a slender four hundredth advantage to a more commanding 3.92 rating points where they to win by more than 15 points - an outcome which would still leave the All Blacks second and more than two and a half points above Australia.
New Zealand will regain the number one spot if they can overturn South Africa, having lost the position they had held for 11 months on the back of their defeat by the Springboks in Bloemfontein at the end of July.
Their rating will improve by seven tenths with victory in Hamilton, although if they were to achieve a winning margin of more than 15 points, New Zealand would move out to 91.42 points and just over two above South Africa.
European quest for RWC 2011 resumes
The Tri Nations is not the only competition taking place this weekend which could have an impact on the IRB World Rankings with the European Nations Cup 2010 resuming with the Division 2A match between Ukraine and Poland in Kiev.
Only Division 2A and the top tier remain part of the region's qualifying process for Rugby World Cup 2011 with Ukraine and Poland both eager to finish top and earn a meeting with Lithuania in May. The winner of this match will then face the third place team in the top tier for a place in the cross-continental play-off.
Both sides are currently tied on 10 points - having won three and lost one - at the halfway stage of the two-year European Nations Cup, Ukraine occupying top spot by virtue of a superior point differential. The three other sides are not out of contention yet, though, with Belgium and the Czech Republic on seven points and Moldova on six.
History is on Ukraine's side with them never having lost to Poland in seven previous meetings, their 13-12 victory in Lodz last October the narrowest margin of victory. The last time the two sides met in Kiev was six years earlier, Ukraine winning 20-11.
Poland, though, are the higher placed team in the IRB World Rankings, albeit only by a single place and 0.25 rating points. If Ukraine can maintain their unbeaten record against them, then the sides will swap places with the hosts taking over 30th spot.
However Ukraine could also climb above Brazil and Kazakhstan to 28th - their highest position for nearly four years - if they win by more than 15 points, something they have only done once in seven previous meetings.
Poland would slide another place, below Belgium, in this instance. They will, though, rise to a new high of 26th if they can beat Ukraine for the first time - regardless of the winning margin - and condemn their hosts to a fall of two places to 33rd.
The IRB World Rankings update every Monday at 12:00 UK time.
