The midfielder arrived at Arsenal on transfer deadline day for £45million from Atletico Madrid, but he only trained for the first time on Thursday after being away on international duty with Ghana.
It means Dani Ceballos and Granit Xhaka are likely to play in midfield for Arsenal, although Mohamed Elneny is pushing to start too.
In defence, Mikel Arteta is expected to be have Kieran Tierney available – who has been in quarantine after being in close contact with his Scotland team-mate Stuart Armstrong, who tested positive for Covid-19 last week.
Tierney has since tested negative for the virus and Arsenal want him to play, with Celtic boss Neil Lennon confirming the Gunners have permission to play him after revealing he has not been allowed to select his players who were in close contact with Armstrong.
That means a back three of Gabriel, Tierney and Rob Holding are likely to start at the Etihad, unless David Luiz is given the nod instead.
In attack, Alexandre Lacazette is expected to lead the line and he will be flanked by Willian and captain Pierre-Emerick Aubameyang.
Predicted Arsenal XI to face Manchester City (3-4-3): Leno; Holding, Gabriel, Tierney; Bellerin, Ceballos, Xhaka, Maitland-Niles; Willian, Lacazette, Aubameyang