Manchester City striker Sergio Aguero is still unavailable because he is isolating after coming into close contact with someone who tested positive for Covid-19 and manager Pep Guardiola does not know when the Argentine will return.
Aguero was expected to start in City's FA Cup third-round tie at home to Birmingham City on January 10 but did not feature in the matchday squad as they won 3-0.
Guardiola admits he is missing the striker.
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"Sergio is not ready for tomorrow. He is still isolating. I don't know (for how long)," Guardiola told reporters on Tuesday.
"We need Aguero, we miss him. The numbers speak for themselves, the best striker in our history.
"He can win games himself and for a long time he is not with us but we have not sat here complaining but moved forward with the players that we have and found alternatives."
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Guardiola added that defender Aymeric Laporte will also miss the Villa game but the centre back had returned to training and could feature on Saturday when City travel to fourth-tier side Cheltenham Town in the FA Cup fourth round.
City are second in the Premier League table with 35 points after 17 games, two points behind leaders Manchester United who have played a game more.
Guardiola's side have won their last five league games but the Spaniard said they can still improve.
"The mood of the team after winning a lot can suffer and right now it is in the right position. We just expect to be consistent when the results are not good because it is still a long road to run," he said.
"I don't know what is going to happen in the future... I just want to know and feel what we have to do tomorrow to beat our opponents Aston Villa."
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