Pep Guardiola has reaffirmed his belief in Manchester City's turnaround despite confirming a fresh injury blow, with defender Rúben Dias out for up to a month.

Last Sunday's dramatic 2-1 defeat to Manchester United compounded City's crisis, with the Premier League champions losing eight of their last 11 games and sitting nine points behind leaders Liverpool.

Guardiola claimed he was "not good enough" after the match at the Etihad Stadium but remains confident in a breakthrough in form, with City visiting Aston Villa on Saturday.

"We were close to winning and we lost the game," Guardiola said of the Manchester derby. "I was not happy and had to be honest with myself.

"You fall down six times, you have to stand up seven. "I am fine. I am a normal person with feelings like all of us.

"When a situation is going well we are better and when it is not going well professionally we are more [focused] on what we have to do.

"Sooner or later, we will turn it around. I don't know when."

But City could be facing a crisis in defence, despite Manuel Akanji and John Stones returning to training, with Dias picking up a muscular injury against United.

"He's [Dias] out for a long time. Three or four weeks. Muscular issue. After 75 minutes against United he felt something but he is so strong so stayed on the pitch.

"Ederson I don't know if he will be ready [for Villa].

"Manuel and John are back training with us. That is good for us."

Villa are seventh in the table, two points and two places behind City.