The English beat Tonga 36-20 on Friday night to qualify for the World Cup quarter-finals, while Ireland's dreams of making the last-eight were quashed by the Pumas. Seventh is their lowest ranking since February 2006.
Fiji, the surprise quarter-finalists, are the big movers in the latest rankings, with Wales, the team that the Islanders thrillingly beat 38-34 in Nantes on Saturday, shifting down two places to tenth - their lowest position since the rankings began back in October 2003.
The Fijians are up to ninth place from eleventh after qualifying for the World Cup's knockout stages for the first time since 1987. It is their first time to be ranked in the world's top ten sides since 2005.
The Southern Hemisphere's dominance of the premier positions remains with World Cup favourites New Zealand leading Australia, South Africa and Argentina in the top four. The Pumas have closed the gap on the Springboks to less than one rating point.
Italy and USA have both lost ground - moving back to 11th and 19th respectively - due to their failure to make the quarter-finals, while Scotland, the team that Italy faltered against in their final pool game, have gone from eighth to sixth position.
IRB WORLD RANKINGS (As of October 1):
(1) New Zealand 93.38 rating points
(2) Australia 87.73
(3) South Africa 86.44
(4) Argentina 85.78
(5) France 84.63
(6) England 80.10
(7) IRELAND 78.66
(8) Scotland 77.09
(9) Fiji 75.82
(10) Wales 74.08