The influential midfielder was withdrawn at half-time of last weekend's draw at Swansea in the Barclays Premier League due to fatigue and was rested for the midweek win over West Brom.
But those were precautionary measures by manager Roberto Mancini and the Ivory Coast international, who scored the winner in the cup final two years ago, hopes to be on top of his game, saying: "I am good. Sometimes it is difficult to play all the games at the same level and sometimes you can get an injury."
He added: "But we have worked on that, trying to keep injury far away and try to concentrate on delivering at the weekend.
"I am already fit. I started training three days ago and I am well in now. I want to deliver a good game and help the team to achieve something important."
Winger Scott Sinclair is out of contention after undergoing surgery to remove a blood clot in his shoulder but otherwise City have no major injury concerns.
Back-up goalkeeper Costel Pantilimon is expected to be selected ahead of England number one Joe Hart having played in all the previous rounds.
Victory for City would provide handsome consolation after their failure to defend the Premier League title they won last season.
Midfielder James Milner said: "We are bitterly disappointed how the league went this year. The main thing is that we win a piece of silverware at the weekend, do that and take the momentum of winning a trophy into next season and have a good league campaign.
"It's tough to get to any final. There's one game standing between you and a piece of silverware and it's an awesome feeling to win it."
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