City were on the verge of dropping points today against Crystal Palace, but super substitute Iheanacho found the net in stoppage time.
De Bruyne came off the bench to replace Aguero, who might have picked up an injury. City were heading for their first draw of the campaign.
18-year-old Nigerian, Kelechi Iheanacho came on in the 89th minute for Wilfried Bony and worked magic by getting his first premier league goal in a crucial match.
City are now five points clear of Arsenal at the Premier League summit and 11 points better off than ailing champions Chelsea.