The midfielder concedes the Reds have only themselves to blame for 3-0 defeat at the Etihad on Tuesday night, but promises much improved performances in two-legged clash
Goals from Sergio Aguero, Yaya Toure and James Milner on Tuesday saw off the Reds in the Premier League on Tuesday and allowed City to open up the gap once more at the top of the table.
Spearing admits his side have themselves to blame for their defeat in the league, but is adamant Liverpool will be much improved when they return to the Etihad for the first leg of the semi-final.
"The goals we conceded were our own fault and we could have done better to prevent them," Spearing told the club’s website.
"I thought as a team we did quite well overall. We used the ball well at times and just some lapses in concentration cost us the game.
"Sometimes it is the small details which can cost you in these games. When it was still 0-0 Jordan Henderson put a great ball through to Stewart Downing, and he was unlucky not to score when Joe Hart made a great save. If that had gone in it could have been a different story.
"We know what we have to do better when we come back here next week in the League Cup and we will be better.
"We will get at them right from the off and I still feel we can cause them a lot of problems. They are going to be two massive games and I don't see any reason why we can't make the final."
The 23-year-old also revealed his happiness at Steven Gerrard's return from injury and is hoping the veteran can make the difference in the two legs against Roberto Mancini’s men.
He added: "We have Steven Gerrard back now and he is a massive influence on the team and we will go into the two games with confidence.
"Before we can think about that though we have to get ready for our next game which is the FA Cup against Oldham.
"It's another important game for us and we want to get back to winning ways in front of our own fans."
Spearing also offered his condolences for the family of former Liverpool and Everton man Gary Ablett, a figure the midfielder greatly admired.
Spearing said: "It's a tragic loss for the game as well as the football club. I think all Liverpool and Everton fans appreciate what he did for both clubs.
"For me personally he was a great manager and a big influence. I played in the reserves for three years under Gary and we won a treble in 2008 which was fantastic.
"I had a lot of respect for him and have got a lot to thank him for, and it really is so sad."