The round of 16 set up is actually a bit of a joke. It's surely not right that in a cup tournament, it's already pre determined who you're likely to get before a ball is kicked. Instead why don't they have a further draw immediately after the groups for the round of 16. Group winners earn a seeding, runners up non seeded. Therefore the incentive is there to win the group and avoid 'match fixing' so as to deliberately dodge a certain team in the next round.