The team which struggled so badly against Spurs in the opening game of the season eventually gelled after some early disorganisation.

It took just 12 minutes for new boy James Milner to make his mark with an inch-perfect pass for his former Aston Villa team-mate Gareth Barry to slot home.

Earlier, the impressive Adam Johnson had let fly at the Liverpool goal but succeeded only in hitting the side netting.

Time and again he worried the visitors' defence with his menacing charges, running rings round Daniel Agger.

As early as the third minute Martin Skirtl was cautioned for felling the City winger.

Six minutes after the break City were two up, Micah Richards' thundering header going through the grounded Pepe Reina's legs with the ever-effervescent Carlos Tevez in close attendance.

How the watching Sir Alex Ferguson must have reluctantly agreed with the sarcastic chants of the City faithful to sign the Argentinian up.

Liverpool had their moments. Steven Gerrard might have brought the Reds back into contention when he struck a post from 30 yards and then Joe Hart made a super double save from David Ngog and Fernando Torres in the resulting scramble.

Torres flashed a shot wide on 66 minutes but it was all over when Skirtl brought down Johnson and Tevez made no mistake from the penalty spot.

Mancini remained cautious about City's performance despite the emphatic result, declaring: "I was very happy tonight because there were six English players [in the team]."

Liverpool boss Roy Hodgson conceded: "I don't think we've done very well tonight. "We defended poorly for those goals. They took charge of the game."

He added that but for Hart's double save at a crucial time the result might have been very different.