Manchester City manager Pep Guardiola has acknowledged Sergio Aguero's importance to the team but says he will not rush the Argentine striker back into action.
Aguero injured his hamstring in City's 1-1 Premier League draw at West Ham United last month, only a week after making his first start of the season following knee surgery.
He was an unused substitute in City's 2-0 defeat by Tottenham Hotspur on Saturday, which left them 13th.
Guardiola's side have scored only 10 goals in eight league games, 17 fewer than at the same stage last season. They have also failed to score more than once in each of their last six Premier League games.
"I will not say we don't need Sergio -- we need him. But Sergio, at 32, was five months injured with a difficult and dangerous injury," Guardiola said. "He came back for 50/55 minutes and was injured again.
"I want him to be fit because I know what he has done in the Premier League -- he is important for us. But we have to be careful and make sure that he doesn't come back and get injured again.
"We have to wait for the right moment to put him back. Hopefully, he can come back and maintain the regularity to play games."
City face Olympiakos in the Champions League on Wednesday.