City's quest to cement second place in the table continues this evening when it hosts West Bromwich Albion, three days after the club had to settle for a point at Swansea City.
After the 0-0 draw with the Swans, Mancini expressed his frustration at how his players had failed to make the most of their opportunities during the game.
And on the subject of negotiating league fixtures in the last few days building up to a Wembley trip, the Italian said: "It is difficult and (the Swansea match) was difficult as our concentration is on the final.
"But we need to play these games and for us it is important to win."
Mancini has emphasised that it is far from ideal to have to play four days before a cup final, but acknowledged that Wigan - which hosts Swansea tonight - is in the same boat.
"It would be better to have one week (of unbroken preparation)," Mancini said.
"But we play Wigan and it is the same for them. Then we have four days to prepare."
Mancini, who rested striker
Midfielder Yaya Toure was withdrawn at half-time at the
Mancini said: "We need to change as we will be playing a second game in three days and we need some players to be fresh."
Asked if he expected to play against Albion, the centre-back said: "I don't know, but the manager has got loads of options and I am sure that whatever side he puts out will be a strong side.
"It's a game that we have to win. There is no other way to think about this game.
"Until we are safe for that Champions League spot we have to play the games like every other game.
"It (Saturday) is a big, big day for the club - it's massive and everyone realises that.
"But it would be nice to win the game against West Brom. That would set us up really nicely.''
Someone certain to not be involved against the Baggies is
After this evening's clash, City's remaining league games see it travel to Reading and then host Norwich.