Many with me had understood ClanBase's Starcraft Nation Cup rules as the following: "Top two countires advance from each group". I spoke to 
Lord_Marine who stated: "alot of people thought it was top 2", and "its been top 4 from the start". This means that the match between
Poland and 
Sweden will in fact not be a decider game, and that it is very likely both countries will advance to the playoffs. A better position in the group will result in a better position in the playoffs, though.Links
ClanBase.com - Official homepage
