Roberto Mancini insists he knows Manchester City can win the title next season after the Blues beat rivals United 2-1 at Old Trafford.
The victory, thanks to goals from James Milner and substitute Sergio Aguero either side of a Vincent Kompany own goal, moves the defending champions to within 12 points of runaway leaders United with seven games to go.
Mancini remains defiant the title race is over for this year but is confident his side can regain the crown next time around.
He said: "This win is not important [for next season] but we know that we can win the title next year.
"This year we know we made some mistakes. We can do nothing. The title is gone. Now we need to continue to play like this.
"This win was important for us for the second position but this shows that we did not deserve to be 15 points behind. The title is finished.
"It does not matter how many points behind. We are not close to them. They score more than us and that is the difference."
City opened the scoring when Milner's shot deflected off Phil Jones and in, but United boss Alex Ferguson was upset as Carlos Tevez appeared to be offside, although he did not touch the ball.
"The first goal, certainly Tevez is interfering with play," said Ferguson. "But the linesman on the other side? There is no way he was giving that.
"It was disappointing as he was clearly in the road of the goalkeeper. If that is not interference then I don't know what is."
Robin van Persie's free-kick was not dealt with by Joe Hart for United's leveller and Phil Jones's wayward header came off Kompany's back and found the net.
But Aguero, who had replaced Samir Nasri just seven minutes earlier, raced through the United defence in the 78th minute to fire into the roof of David De Gea's net.
United seek immediate bounce-back
Despite the defeat, Ferguson remained upbeat as he prepares his side for a visit to Premier League strugglers Stoke on Sunday.
"We won't be relaxing," he said. "If you look at the history of the club we always make it difficult for ourselves.
"We put supporters on the edge of their seats every year. The only other plus point is that there are only seven games left now.
"Each game goes on and you whittle them down. We go to Stoke on Sunday and it will be a big effort, the support will be great. We'll have a go.
"It's a healthy lead but we're not taking anything for granted.
City now look forward to an FA Cup semi-final with Chelsea on Sunday at Wembley but may have to do so without David Silva as the Spaniard limped off in the latter stages at Old Trafford with a hamstring problem.
Mancini is also expecting a difficult game against the Cup holders as he looks to finish off the season with some silverware.
"David has a hamstring problem," he said. "Maybe it is not so bad, but I don't think he will be ready for Chelsea.
"I think it will be a different game. It is a semi-final. Chelsea is in a good moment, they play well and it will be difficult.
"It will be a good game, probably, but it will be different. Semi-finals are different from championship games."