A solitary goal was scant reward for the dominance of Pep Guardiola’s men as the Catalan was rewarded for naming a strong line-up against the Championship side.
Riyad Mahrez and Gabriel Jesus missed glorious first half chances, while Nicolas Otamendi and Benjamin Mendy hit the woodwork before Aguero finally made the breakthrough.
Despite failing to add to their tally, City were never troubled as they moved into the last eight and maintained hopes of a cup treble after lifting a third consecutive League Cup on Sunday and beating Real Madrid 2-1 in the first leg of their Champions League last 16 tie.
Leicester also booked their place in the quarter-finals with a much-needed 1-0 win over Birmingham thanks to Ricardo Pereira’s late header.
The Foxes have won just one of their last seven Premier League games to stall their charge towards the Champions League next season.
Brendan Rodgers’s men were again without Jamie Vardy through injury and needed right-back Ricardo to get the only goal when he headed home Marc Albrighton’s cross eight minutes from time.
