England have slipped to fifth in the International Rugby Board world rankings after their loss to Australia.
Argentina's 22-14 win in Italy has lifted the Pumas above Martin Johnson's side into fourth ahead of the draw for the 2011 World Cup on 1 December.
England must finish in the top four if they are to avoid one of the three Tri-Nations teams in the group stages.
They must now either beat South Africa or New Zealand at Twickenham, or hope Ireland beat the Pumas on Saturday.
Ireland have a huge incentive for victory themselves after their disappointing 22-3 defeat by New Zealand.
IRB WORLD RANKINGS 17 NOV
As things stand, Scotland - who came close to toppling South Africa on Saturday - are heading for the third tier of seeds, which means they will have two major nations in their group.
France, who have beaten Argentina 12-6 and the Pacific Islands 42-17 in their autumn Tests to date, (although the latter did not count towards the rankings), could also move into the top four if they beat Australia on Saturday and results elsewhere go in their favour.
The draw for allocating the pools for the next World Cup will take place in London on 1 December.
As in 2007, there will be four pools of five teams, with the top three positions in each pool filled by the 12 pre-qualified teams from the last World Cup.
Those 12 are Argentina, Australia, England, Fiji, France, Ireland, Italy, New Zealand, Scotland, South Africa, Tonga and Wales.
The IRB rankings will determine which seeding band the countries find themselves in, with one-to-four in the rankings forming the top band, five-to-eight the second tier, and nine-to-12 the third.
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