Fernandinho winning fitness fight
The Brazilian has been out for the past fortnight with a muscle strain but has trained ahead of the first leg of the last-16 tie at the Etihad Stadium.
Manager Manuel Pellegrini said: "He has a chance. He is in the squad list for tomorrow. We will see tomorrow who can start but he has worked without any problem."
Fernandinho's availability gives City a big lift for what will be one of the biggest nights in the club's history.
As expected, however, top scorer Sergio Aguero will not be involved, having failed to overcome a hamstring injury in time.
Pellegrini, speaking at his pre-match press conference, said: "He is not in the squad list.
"We will see if he can be fit on Saturday, but maybe that is also difficult."
Defender Matija Nastasic is also unlikely to feature, having not played an active part in the open training session at Eastlands.
Fernandinho has formed a solid midfield partnership with Yaya Toure this season, an arrangement which has allowed the Ivorian greater freedom to power forward.
With Fernandinho absent, Toure was criticised as City lost to Chelsea in the Barclays Premier League a fortnight ago and were subsequently held to a goalless draw at Norwich.
Pellegrini believes those judgements are unfair and that Toure was playing as he had ordered.
He said: "Yaya is a very important player for us. I have listened to some questions about the way he plays and Yaya plays the way I want him to play.
"He stayed only defending against Norwich because we did not have another defensive midfielder, but I think we lost an important midfielder attacking. He scores a lot of goals and brings a lot of creativity to our team.
"Playing in there with Javi Garcia or Fernandinho is the way I want him to play, where he is free and can give us a lot of offensive moments. But he knows also he has to defend and he can do it."
As ever, Pellegrini has vowed to continue playing the same style that has served his side so well on most occasions this season.
Pellegrini did receive criticism of his tactics after the league loss to Chelsea, but stuck to his guns and turned the tables on the Londoners in the FA Cup last weekend.
Four-times European champions Barcelona may boast a formidable reputation, but Pellegrini does not intend to change even for them.
He said: "Of course when you play against Barca you always must consider important things, but the most important thing is to continue being the same team you see every week in Premier League, to continue having the same style of play and the personality.
"You cannot continue without thinking they have (Lionel) Messi and other important players, but we are not just going to think about defending, but what we can do with the ball. That is the most important thing."