France's slip from 86.90 rating points to 83.13 has demoted them from third to fifth place, allowing South Africa (85.40) to take third spot and make it a Southern Hemisphere 1-2-3-4.
Argentina's win in Paris gained them 3.77 rating points and also their highest ever placing in the world rankings as they continue their considerable progress under Loffreda - they were ranked ninth just over twelve months ago.
During the World Cup, ranking points are worth double their normal value.
Ireland, whose victory over Namibia last night made no difference to their rating of 81.12, meet Argentina at Parc des Princes on September 30 in what could be the Pool D decider.
The Irish will not be getting ahead of themselves though as they have to take on the might of 17th-ranked Georgia and the wounded French before they clash with the Pumas.
IRB WORLD RANKINGS (As of September 10):
(1) New Zealand 93.38 rating points
(2) Australia 87.03
(3) South Africa 85.40
(4) Argentina 84.82
(5) France 83.13
(6) IRELAND 81.12
(7) England 78.89
(8) Wales 77.53
(9) Italy 75.37
(10) Samoa 74.97
(17) Georgia 66.38
(24) Namibia 57.15