Eight seed teams are put in one bowl, and there are also eight bowls. Each bowl has eight identical teams, such as bowl 1 with eight Arsenal, bowl 2 with eight Manchester City and bowl 3 with eight Dzenit. . . . . . There is a name on the bowl, and the shell of each ball is the same. You can't see which team it belongs to.
After the seed team drew out Real Madrid, they found out from eight bowls that could compete with Real Madrid. For example, there are five eligible ones. Put one of each bowl together, such as bowl A, and you can draw it.
After the second seed is extracted, the qualified seeds that have been extracted are reduced accordingly. Take it out again and put it in bowl B, then smoke it, and so on.
1/8 lottery rules, the home and away games have been decided, and the group is the first (the seed team you said).