The forward suffered a knee injury in the early stages of Egypt’s FIFA World Cup qualifying match with Burkina Faso on Tuesday evening.
City have said that Marmoush, who has scored eight times in 28 appearances since joining in January, will return to Manchester for further assessment, although initial scans ‘indicate he will not be available on Sunday’.
Marmoush has featured in all three of City’s Premier League fixtures so far, coming on as a substitute in the 4-0 victory at Wolves and starting the defeats to Tottenham Hotspur and Brighton & Hove Albion.
Pep Guardiola will, therefore, need to make at least one change in attack, although he will also have to factor in Rayan Cherki’s injury, with the summer signing from Lyon now sidelined for two months.