As group winners, both Man City and Arsenal will be drawn against a team who finished second in their group.
This means there could be a repeat of last season's Champions League final between Man City and Inter Milan, after the Italians failed topple Real Sociedad and finished as runners-up in Group D.
Teams that finished third will drop into the Europa League play-offs, where they will face a two-legged tie against a team who came second in the Europa League groups.
Those who finished fourth, including Man Utd, Newcastle and Celtic, bow out of European football altogether.
The draw for the next stage of the Champions League, Europa League and Europa Conference League will take place on Monday 18th December from 11am GMT.
Final Champions League group tables
Who can Man City and Arsenal be drawn against?
At this stage of the competition, teams cannot be drawn against clubs they faced in the group stage nor those from the same federation.
It means Man City and Arsenal could be drawn against one of the following teams:
Man City possible last-16 opponents: FC Copenhagen, PSV, Napoli, Inter Milan, Lazio, PSG, FC Porto
Arsenal possible last-16 opponents: FC Copenhagen, Napoli, Inter Milan, RB Leipzig, Lazio, PSG, FC Porto
