We have been here before. A southern hemisphere clean sweep in this weekend's Rugby World Cup quarterfinals would be unprecedented, but it is not the first time the possibility has loomed. Back in 1999, the last time the tournament was hosted in Britain, we also saw a quarterfinal weekend composed entirely of North v South clashes.

On that occasion the South got three through, with the whitewash averted by France's 47-26 defeat of Argentina at Lansdowne Road. That extent of southern dominance was in itself a break with the usual pattern -- every other World Cup has seen a 2-2 split between North and South at the semifinal stage.

With that in mind we crunch the numbers to see who holds the edge going into this weekend's last eight encounters. 

North vs. South

Thierry Dusautoir© MARTIN BUREAU/AFP/Getty Images

1 - only once has the north had the edge in terms of these inter-hemisphere battles. That was in 2007, and the extraordinary day on which England ambushed Australia in Marseilles and France beat the All Blacks in Cardiff. That outweighed Argentina's defeat of Scotland.

1 - northern hemisphere third-place playoff win when facing southern opposition. By contrast sides from the south have won four against teams from the north.

2 - semifinal victories for northern hemisphere sides over their southern counterparts.

3 - last-eight victories for northern hemisphere sides against the big three (Australia, New Zealand and South Africa).

4 - north-south quarterfinals since 1999. There were none at the last World Cup in 2011.

6 - finals that have been contested between northern and southern hemisphere sides, with only one northern victory.

7 - North v South semifinal clashes, all of which came in the first four tournaments.

10 - wins for southern hemisphere nations in those matches, with only six victories for nations from the north.

16 - of the 28 World Cup quarterfinals before this tournament have been played between northern and southern hemisphere sides.

South Africa vs. Wales

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0 - World Cup wins for Wales against the four southern hemisphere sides left in the tournament since the turn of the century. Their overall tournament record against those teams is 3-9.

2 - Welsh wins against South Africa in 30 attempts, there have been 27 defeats and a draw.

France vs. New Zealand

Philippe Bernat-Selles© Ross Kinnaird /Allsport

2 - World Cup wins in six attempts for France against the All Blacks. But we all know about the two in New Zealand's losing column -- the only times they have played the French in World Cup matches in the northern hemisphere, famous defeats in 1999 and 2007.

13 - wins in 15 World Cup games for New Zealand against France, Ireland, Scotland and Wales.

Ireland vs. Argentina

© Christophe Simon/AFP/Getty Images

1 - in their five games previous to that run, the Pumas won just one match.

5 - World Cup wins for Argentina against the four northern hemisphere sides left in the tournament, without defeat, since losing to Ireland by a point in 2003.

Australia vs. Scotland

© Jonathan Wood/Getty Images

10 - World Cup games against the big three southern hemisphere sides for Scotland, without a single win.

11 - World Cup victories for the Wallabies against the four northern hemisphere sides remaining, in 14 games. Two of their three defeats date back to 1987.