Manchester City's future is set with Kelechi Iheanacho and Kevin De Bruyne

Before the Manchester derby, Jose Mourinho said that the absence of Sergio Aguero made Manchester City more difficult to play against. "When Sergio Aguero is available he plays, we know their formation," said Mourinho. "We have to reduce the unpredictability."

It seemed like a ridiculous suggestion. It was a perfect quote to fuel the Mourinho vs. Pep Guardiola narrative and reinforce the rivalry as one that's more about a tactical chess match than anything the players do as individuals. But as it turned out, Guardiola didn't change his formation at all with Aguero out. He just put in Kelechi Iheanacho, City's ultra-talented 19-year-old academy product. And he produced just like Aguero does, tallying an assist for the opening goal and scoring the winner as well in a 2-1 victory for City over Manchester United.

For the entire time he was on he combined with Kevin De Bruyne, who scored the opener and set up Iheanacho's goal. De Bruyne had six shots, six passes that set up shots for others, and his 83 percent pass completion was impressive given the attacking nature of his passing. He was always looking to advance attacks and rarely picked the safest pass available.

The opening goal was very un-Guardiola, on a direct route-one attack. Iheanacho won a header off a long ball from Aleksandar Kolarov, perfectly flicking it into the path of De Bruyne. The second goal featured De Bruyne surprisingly hitting the post from a shot he had no business coming close to scoring on, and Iheanacho reacted perfectly.

City fans will have been thrilled to see their younger talent start this season so strongly. In earlier games, Raheem Sterling has shined, and Leroy Sane had some dangerous moments in the second half of Saturday's match when he came on as a substitute to make his Premier League debut.

One of the biggest concerns about City over the last few years has been how they're going to transition away from an aging core of star players and continue to be competitive, since they've been extremely dependent on 33-year-old Yaya Toure, 30-year-old David Silva, and the extremely injury-prone Aguero. But the derby shined a light on the work that director of football Txiki Begiristain has been doing to slowly but surely overhaul the squad and transition away from the players who defined the Roberto Mancini and Manuel Pellegrini era at City.

Iheanacho and De Bruyne have proven that they're ready to lead City's attack into the future. Sane, Sterling, and the youngsters they have stashed elsewhere — Gabriel Jesus, Patrick Roberts, Marlos Moreno and Oleksandr Zinchenko — will join them. No one's worried about the age of City's top players anymore.