Teams ranked one to four will all avoid each other in the group stages of the tournament, as will teams five to eight.
As things stand, Scotland are ranked ninth by the IRB, meaning they would face two seeds in their pool.
However, the Scots could still climb back into the top eight at the expense of Ireland if results go Frank Hadden's way this weekend.
Scotland need to beat Canada and hope that Argentina continue to be Ireland's bogey team by gaining a win over Brian O'Driscoll and co at Croke Park.
The Pumas themselves have plenty resting on the match against Ireland as a victory would see them maintain fourth spot and guarantee a place among the top seeds. Finishing fourth would be a huge boost to any side as it would mean avoiding the All Blacks, Springboks and Wallabies until at least the quarter-final stage in New Zealand.
England could still overtake Argentina with victory over South Africa or New Zealand or an Irish victory in Dublin, while France could also finish fourth if results go their way.
The Rugby World Cup will again be split into four pools of five teams, with the top three slots in each pool filled by the 12 pre-qualified teams from the last World Cup.
All four Home Nations, the three southern hemisphere giants, and Argentina, Fiji, France, Italy and Tonga are the teams who have already qualified based on their performance in France in 2007.