Pep Guardiola claimed Manchester City have been playing through a state of emergency.
City are expected to welcome back injured pair Phil Foden and Jack Grealish for Wednesday's trip to Aston Villa but are again likely to be without Kevin De Bruyne.
De Bruyne is now out of self-isolation, although not ready to participate in training.
Defender Aymeric Laporte also misses Wednesday's match through suspension, with City only naming six outfield players on his bench at the weekend.
'We are in an emergency in the squad,' Guardiola said. 'We have few, few, people. We never complain, I trust a lot in the squad and other players come in but December is the toughest month of the year so we are in trouble because we have few players.
'Kevin is back but he needs time to be fit. All the people who had Covid say it drains and Kevin needs time to show his form.
'Phil and Jack are still in the same situation, maybe tomorrow they can play but not a lot of minutes.
'We are going to see after they train today. We are in a difficult position because a lot of players have already played a lot of minutes.'
Guardiola also backed Grealish to become a hit at the Etihad Stadium and believes he is getting to grips with the demands placed upon him after a £100million summer move from Villa.
'I would say he's settled perfectly, he knows many English players,' Guardiola added. 'He's not a problem, he play good but has to find a bit of time. If you analyse the games, he's not played bad.
'With the quality it's difficult to play bad. It's different for him here but he did it incredibly well, what he did at Villa was amazing, helping them get up and stay there.
'We want to see it (from him) now. We've six or seven months with a lot of nice things, we want to see it this season.'