Pep Guardiola suggested Jack Grealish was dropped to the bench for the Manchester derby because he wanted a left-footed player on the left wing.
Guardiola made three changes from his City side that beat Club Brugge in the week, with Grealish, Riyad Mahrez and Aymeric Laporte dropping out as Kevin De Bruyne looked to be deployed in the false nine role with Phil Foden and Gabriel Jesus either side of him.
Grealish has started most of City's big games this season, including at Chelsea and Liverpool, but was only a substitute at Old Trafford as Guardiola mixed things up against Ole Gunnar Solskjaer's United.
Explaining his team selection, Guardiola offered a simple reason for selecting Foden on the left and Jesus on the right - to offer balance.
Asked why Grealish wasn't starting, he told Sky Sports: "We want a left foot on the left side, right foot on right side. Basically that is the reason."
With United naming a back three, with Aaron Wan-Bissaka and Luke Shaw at wing-back, presumably Guardiola wants Jesus and Foden to stay wide and pin those wide defenders back.
But he trusted his players to keep ontop of their emotions and take advantage of moments when they are on top.
He said: "For them it's not the first important game in their career, not the first time we're here. We have to be emotionally stable in good and bad moments. In this game you have to be like that. The players are professional, they're in football for this kind of game.
"To be able after 10 minutes to score four goals, that would be the key. Before the game I never think about the key, what would be most important for the rest of the game. Let's see who's more stable in the bad moments stick together, in good moments be clinical, ready to suffer. We have to fight and be conscious that football, 90 minutes many things can happen. Do it until the end."
