Aguero needs to sit out again due to a stomach virus.
has been sidelined again with a stomach virus and
says he will deal with Aguero step by step and do what is best for theCitizens
"With Sergio it is one step at a time,"
he explained to reporters.
"He made one training session, he was four months out and there are players who, for them, not to be in the squad would not be fair to them.
"That is why sometimes I have to handle the balance of the team. For me it is so tough, to drop Nathan Ake after he was exceptional against Marseille.
"He could not be selected today because there is this rule that there cannot be 19 or 20 players when all the players are available for the squad, some are at home.
"Hopefully Sergio will be back, make more training sessions and as many minutes as possible to come back as soon as possible."
He also talked aboutLaporte
who is waiting to regain his spot in the team.
"He deserves to be in the team but John Stones and Ruben also deserve to be in the team,"
Guardiola said of Laporte
"They played incredibly well in the last games and didn't make one single mistake.
"Aymeric played so well against Marseille and that is the point - team selection. Nathan Ake played extraordinarily well against Marseille but I have to make a selection. They didn't make mistakes.
"What they have to do is work harder, better and the moment will come, and when the moment comes have a good performance.
"Every player in every squad has incredible skills, like United, Spurs and Liverpool. But it is about how you perform right now. Right now. John and Ruben performed brilliantly, so they play."