Roberto Mancini says Manchester City can regain the Premier League title next season, having written off their hopes for the current campaign.
City trail league leaders Manchester United by 12 points after beating their local rivals 2-1 at Old Trafford.
"We know we can win the title next season but this year we made some mistakes," the City manager declared.
"It is unfortunate, we can do nothing. This season the title is gone."
Substitute Sergio Aguero's brilliant late individual goal gave City their second successive win at United, who remain on course to win their 20th title.
"The championship is finished," added Italian Mancini.
"United have won a lot of games and they lost their last game against Norwich in November, a long time ago."
Mancini was delighted with how his side performed in the derby win, saying: "We are happy. We played well and we deserved to win.
"We dominated the other game against Manchester United at the Etihad but lost and I didn't know how it was possible. But that is football; today is the same.
"It was important for us to take second position but I think we showed we don't deserve to stay 15 points behind.
"They have had more consistency in this championship because they won more games but instead we lost points when we probably deserved to win.
"We showed we deserved to stay closer to the title but it is finished. If we lose the title by 15, 12 or 18 points, it does not change anything."
Mancini claimed his squad had been undermined by injury problems as he said: "This season we had some problems with players injured. We are not a team that can lose three or four players.
"We can't lose Yaya Toure and Vincent Kompany together. We are not so strong that we can lose three or four players like this."
Looking ahead to the summer, he added: "We have got three months where we can work well and improve our team."
David Silva, meanwhile, is a serious doubt for Sunday's FA Cup semi-final against Chelsea at Wembley after being forced off with a hamstring injury at Old Trafford.