Cross:
a 1 vs b2
A2 vs. b 1
C 1 pair d2
C2 to d 1
Xia Yan
a 1 vs b2
b 1 vs c2
C 1 pair d2
D 1 to a 1
There are many kinds of international competitions before now, but it is relatively easy to choose opponents with match-fixing, and there are also group A against group C and group B against group D. This is actually of little significance, just changing the name.
Because the lottery is unfair (a strong team is easy to die), it is rarely used in this way.