Gary Neville applauded Sergio Aguero's winner in the Manchester derby - but says the Argentine's lack of goals this season has dented City's title challenge.
Roberto Mancini's side earned a morale-boosting 2-1 victory over their rivals at Old Trafford but remain 12 points adrift of the Premier League leaders and Neville told Monday Night Football he cannot see City overhauling that deficit with seven games to play.
After winning the league on goal difference from United last season, City face the prospect of seeing their neighbours reclaim their crown in the next few weeks - and Neville believes match-winner Aguero's tally of 10 league goals this season is partly to blame.
"Aguero's goal can only be described as fantastic," said the former United and England defender. "He works his way across the United backline and the defenders are scared to challenge him in case they give away a foul.
"He takes an extra touch and then the finish is magnificent. People say keepers shouldn't get beaten at their near post but no goalkeeper in the world would save that shot.
"However, we talk about Aguero being brilliant but we haven't seen the best of him this season; you can talk about City not having Robin van Persie or whoever, but Aguero has only scored 10 goals in the league.
"That's got to be an underachievement and that's why they are where they are."
Although, Neville believes the title is out of City's reach, he reckons the derby win will give the current Premier League champions confidence going into this weekend's FA Cup semi-final against Chelsea at Wembley.
"With seven games to go you can't see the outcome of the title changing," he said. "This result will just delay it because I can't see Manchester United throwing it away; City have given themselves far too much to do to put any nerves into United.
"However, the win gives City a boost ahead of Sunday, their FA Cup semi-final, which is their biggest game of the season.
"With respect to Wigan and Millwall, if City were to win on Sunday, what an opportunity they have to win a trophy.
"In seasons you don't win the league every team that's used to winning trophies will tell you that you need to pick up a trophy to keep the momentum going."
In terms of where the derby was won, Neville believes Mancini's tactical ploy of starting the game with five in midfield gave the visitors control of possession.
And he explained that United only began to build pressure and threaten to win the game when Aguero was brought on to play alongside Carlos Tevez up front, reducing City's numerical advantage in the middle of the park.
"Man City held possession of the game; it was a good away performance from them," he said. "Phil Jones was United's best player, which tells you something about the game.
"In the first half City had good possession and it was difficult for United to get near them - and United had their strongest period at 1-1 because City went two up top with Aguero and Tevez and they had less strength in midfield.
"United started to look like they were going to get some good positions and were pressing City, but then they got done on the counter attack by a fantastic goal.
"However, United were not at their absolute best, which you need to be in these games to get the end product you require."
There was a question mark over James Milner's opener for City, with his deflected drive from the edge of the box passing Tevez who appeared to be in an offside position in front of United keeper David de Gea.
However, Neville refused to be too critical of the officials for not flagging the City forward as offside.
"These are difficult calls for linesmen and refs to give - particularly when none of the United players are complaining," he said.
"Technically it is offside but it is a difficult one to give because there are so many bodies in the way."
Is Sergio Aguero's lack of goals the reason for City's struggle to defend their Premier League title?