The change in rankings comes on the back of a weekend of contrasting fortunes for the two nations. Juan Martin Fernandez Lobbe inspired the Pumas to a 26-12 victory over Wales in the Millennium Stadium.

Ireland continued their run of poor form with a fifth consecutive defeat as they failed to maintain a first-half lead, allowing South Africa to overturn them 12-16 in the Aviva Stadium on Saturday.

With the 2015 Rugby World Cup pool allocation draw taking place in London on Monday, December 3, the leading nations are battling it out to be in the top two bands of seeds for the draw.

The IRB world rankings will determine the seeding for the 12 directly-qualified teams for the next World Cup in England.

The top band of teams, ranked one to four, avoid each other in the pool stages. With Ireland currently ranked eighth, they would be in the second band of seeds for the draw.

But if Declan Kidney's men slip out of the world's top eight, they would be drawn from band number 3 and likely to get a much tougher draw.

This shift in rankings has added an extra element to the meeting with the Pumas on the 24th as both sides will be determined to cement their top-8 ranking.

Ireland, Argentina and Wales are all in a battle for ranking places five to eight, with Scotland, who lost to World Cup champions New Zealand yeserday, holding onto ninth spot.

IRB WORLD RANKINGS (as of Monday, November 12, last week's positions in brackets):

1 (1): New Zealand 92.91 points

2 (3): South Africa 85.50

3 (2): Australia 84.82

4 (5): France 84.58

5 (4): England 83.09

6 (6): Wales 80.60

7 (8): Argentina 80.29

8 (7): IRELAND 79.04

9 (9): Scotland 77.97

10 (10): Samoa 77.14

11 (11): Italy 76.61

12 (12): Tonga 74.22