The 17-year-old who was handed a starter’s shirt by manager Patrick Viera inspired his side win against the U21 Premier League champions who took the lead into the half time break.
Andy Kellett took advantage of a lapse in concentration from the home side just before the break to cross for Ashley Fletcher to slide the ball in.
Iheanacho levelled the game before the hour mark, beating his man and slotting the ball past Kieran O'Hara for another fine goal. City continued to press, with Barker now a real handful on his favoured left touchline.
And they were rewarded when Angelino's effort from a short corner was deflected in. Callum Gribbin test Angus Gunn's goal with a long-range effort, but the former Golden Eaglets forward finished off the visitors.
Iheanacho is expected to join with the rest of his colleagues preparing for the 2015 Fifa U20 World Cup on Monday.