Mancini is not giving up on securing back-to-back Premier League titles despite the huge deficit on Manchester United with just 10 games to play.
But City, who lost out to United in the race to sign Robin van Persie last summer, have scored 18 fewer goals than they had at the same stage last season - one fewer than the Dutchman has managed in his first season at Old Trafford.
And in the wake of a 1-0 win at Aston Villa Mancini said: "At Southampton, we played very well and we lost 3-1.
"We had other games like the one at Villa - against QPR and West Ham - where we missed four or five incredible chances.
"Even in the Villa game, we had other chances to close out the match rather
than winning 1-0. It has been our problem this year and has cost us points.
"We have a lot of chances in every game that we are missing. This is the
difference at this moment."