Like Tuesday's bout of EFL Cup matches, Wednesday's fourth-round encounters gave fans a glimpse into the future with many young players blooded.
Despite there being a London and Manchester derby played, the likes of Antonio Conte and Pep Guardiola stuck to their word about rotating their squads.
Sportsmail assesses the performances of the young stars that played.
SOUTHAMPTON
Lloyd Isgrove
Age: 23 Position: Striker Country: Wales
Started in attack for the hosts - his first for the club - but failed to breach the Sunderland defence. Replaced by Nathan Redmond on 72 minutes.