Are there any rules for cross elimination after badminton doubles group match?

20 12 There will be 64 lottery tables for singles in London Olympic Games. Among them, the top 16 players in the world will be put into the 16 team as seeds. Among them, players from the same country will belong to the upper and lower half according to the ranking, ensuring that they will not fight before the semi-final; And if there are three finalists, it can guarantee that the top two in the world will not encounter in advance. In the group stage, four players in each group compete in a single round robin system, and after three rounds, 1 player is selected from the group to qualify. After the group stage, we will enter the stage of cross elimination.