Manchester City's 2-1 win over Premier League leaders Manchester United on Monday was too little too late for manager Roberto Mancini who is already focusing his attention on next season's title race.

Sergio Aguero's outstanding 78th-minute winner allowed champions City to close the gap on their neighbours to 12 points but it was more of a 'nice-to-have' result than a fate-changing victory for this campaign.

"We know we can win the title next year," Mancini told a news conference after his team's second successive league win at Old Trafford, following last season's 6-1 thrashing.

"This year we have made some mistakes unfortunately but now we can't do anything, the season is gone. It is important we continue to win ... we need to continue to play like this for next season."

Second place in the league is what the Italian is striving for with seven games remaining. City also have the chance of silverware as they play holders Chelsea in an FA Cup semi-final at Wembley on Sunday.

"I think it will be a different game, it's a semi-final and Chelsea are in a good moment," said Mancini who is likely to be without playmaker David Silva after he went off with a hamstring injury on Monday.

Mancini previously said City's timid defence of their title had been partly down to a failure to bring in some quality signings, including missing out on top striker Robin van Persie who joined United in the close season from Arsenal.

The Italian also reckoned a spate of injuries to key players were to blame, saying his expensive squad could not cope with the situation.

"This season we had some problems with some important players injured - Aguero, Yaya (Toure), (Vincent) Kompany ... we are not a team who can lose important players like this," said Mancini.

"We are not so strong that we can lose three or four players like this together."

Whatever happens this season, one thing is for sure in Mancini's mind - City will not trail United by 15 points again.

"No, I think we showed this tonight," he said before adding that United deserved to win what will be their 20th league title.

United manager Alex Ferguson, who has refused to watch a re-run of last season's Old Trafford humiliation at the hands of City, had less to be upset about in his team's performance this time.

"It was a very intense game, very competitive with two of the best teams in the country," he told the BBC.

"I thought we were the better team in the second half but we know Sergio Aguero is a fantastic finisher and we gave him a lot of room for (the winner).

"I was pleased with the second-half performance. There were a lot of plus sides. Van Persie was fantastic today and Wayne Rooney got some time on the pitch after coming back from injury."