Nigeria whiz kid Kelechi Iheanacho scored a hat-trick for the visitors.
The 19-year-old, who also netted against Norwich City in the previous round, scored from close range and netted a penalty inside the opening 24 minutes.
Iheanacho completed his hat-trick late on as he took advantage of some terrible Villa defending to beat Brad Guzan one-on-one, before Raheem Sterling sealed the victory as Manuel Pellegrini's men continued their pursuit of four trophies.
With Sergio Aguero dropping to the bench for City as both sides made four changes, Iheanacho took full advantage of his opportunity up-front with an excellent individual display.
Villa came into the match unbeaten in five games and held City to a goalless draw at Villa Park in November, but they offered little resistance in a dreadful performance.
Courtesy of GHANAsoccernet.com