City begin their defence of their European crown on Tuesday night with a clash against Serbian side Red Star Belgrade at the Etihad.
Following their treble success, the Citizens are favourites to win back-to-back Champions Leagues titles – a feat only Real Madrid have previously achieved.
Additionally, Guardiola will be looking to become only the second manager after Carlo Ancelotti to win the competition four times, but he’s kicking-off this campaign without several key stars.
Captain Kevin De Bruyne remains a long-term absentee due to the thigh injury he sustained in the Premier League opening night win at Burnley.
But their had been hope that the trio of John Stones, Mateo Kovacic and Jack Grealish would be back in time for the Red Star match.
The English duo, who were pivotal to the treble win, have been recovering from thigh injuries, while summer signing Kovacic has been on the sidelines with a back issue.
But Guardiola confirmed in his pre-match press conference, that the three will not be available on Tuesday, but they could well feature in the following game against Nottingham Forest at home.
‘They are getting better, not for tomorrow. Hopefully Nottingham or next games we need it,’ the manager said on Monday.
‘We proved ourselves without them but hopefully they are back soon because we need the competition. We need Jack to compete with Jeremy [Doku], the feeling to play good to be in the squad.
‘Difficult to stay for a long time. It happens, we accept it.’
Summer signing Doku has replaced Grealish in the starting XI since the latter’s injury and looked very impressive in last Saturday’s 3-1 win at West Ham, with the Belgian winger scoring the equalising goal.
‘When you are the wingers against the fullbacks and dribble, is a chance. Support for a winger to dribble to the byline is a chance,’ Guardiola said of Doku when asked where the 21-year-old has impressed.
‘He does it a lot. That’s why I say I was impressed, we knew his quality but didn’t expect the ability to release Julian [Alvarez], Erling [Haaland], Phil [Foden] – go close to the box because this guy dribbles and they have to be there, an incredible threat.
‘For a long time I didn’t see a performance of a winger going again and dribbling with his fullback. It won’t happen every week. He has the quality to do it, go, try do it.’
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