Pep Guardiola will only target January signings for Manchester City who can contribute to the club for the long-term, despite seeing his side's injury crisis deepen over the festive period.

Jack Grealish pulled out of the Blues squad to face Everton on Boxing Day after complaining of a muscle problem in the days before the match, with Guardiola revealing the attacking midfielder had told him he wasn't ready to play after feeling the issue in training.

Guardiola's problems were further compounded by the loss of Kyle Walker, who is suffering from flu, while Nathan Ake volunteered to play and had to come off when he started to feel the fatigue.

READ MORE: Marcus Rashford call made and Amad U-turn - Manchester United predicted XI vs Wolves

READ MORE: Manchester United could be without five players vs Wolves amid Marcus Rashford decision

It meant City were without eight players for the game as fitness problems continue to derail their season and the only two outfield players on the bench with any real senior experience were Ilkay Gundogan and Kevin De Bruyne, neither of whom were ready to play many minutes.

But while Guardiola wants to strengthen his squad in January, he knows there has to be a balance between players who can contribute for the long-term and adding bodies to the group.

"The transfer window in the winter is not easy. Even the players know that we have to add some new players," he said.

"But after when these players come and play in their positions then they are unhappy. But we have a lot (of injuries) and this is a problem. It’s about bringing a player for the next four or five years and we’ll have to see. Sometimes it is not easy. We have to try because this is sustained for a long time.

"Eight important players in general and Gundo was not ready today and Kevin was not ready for 90 minutes and maybe should have come on earlier..

"It's [signings] for a long time. we are in that. And of course, you have to talk with the club and the club will decide."

Guardiola offered an update on Walker and Grealish, and also explained Ake's desire to play.

"Kyle had flu virus. Jack yesterday or the day before in training, he felt something muscular again," he said.

"We spoke with Nathan, Nathan made an incredible effort. Like I said, thank you so much and I appreciate it for the effort they have done. Because he was on the verge for the recovery for three weeks when he needs a little bit more. But the circumstances, the problems that we have, he makes an effort.

"And I said, OK, when you feel the fatigue or feel tired, let us know. In the first part was control, the second half was more difficult just for the fact that was more transitional games with Calvert-Lewin and Broja. So, we had to make an effort and I said, what cannot happen is injury again. So, we have a game three days later and this is what we had to do."