The Argentinian was not risked in Saturday's Premier League win over Aston Villa after recovering from a groin injury.
Aguero could take the place of Mario Balotelli, who serves the final game of a three-match European suspension, while Carlos Tevez is likely to remain an outcast.
Back in action: Aguero is in contention for a place against Villarreal
Defender Micah Richards is also fit after being forced off against Villa with a head injury.
Manchester City's Champions League squad Hart, Pantilimon, Richards, Kompany, Zabaleta, Lescott, Kolarov, Savic, Clichy, K Toure, Milner, Johnson, Barry, Nasri,De Jong, Y Toure, Dzeko, Aguero, Silva.
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