It can be any of them.Can't be GALA as we got them already... I tink?
The mad chance in the rules is
1-2 2nd leg at home until semis
3-4 2nd leg at home until quarters
4-8 2nd leg at home in last 16
But if say Benfica get into the last 16 and beat Arsenal or Bayern. Then they get 2nd leg at home until semis.. if Benfica lost the quarters then the team that beat them inherited it.
Surely it should go to the next placed team in the league phase?
