Man City returned to the top of the table on a famous night at the Etihad Stadium as Vincent Kompany's goal sealed victory over Man Utd.
Mancini's men win 1-0 at Etihad to hit United's title hopes
Manchester City returned to the top of the table on a famous night at the Etihad Stadium as Vincent Kompany scored the only goal of the game against Manchester United.
The derby had been billed as perhaps the biggest game in Premier League history and it was City who prevailed in an absorbing encounter which came close to boiling over at times.
The crucial moment arrived on the stroke of half-time as Kompany climbed highest in the area to beat Chris Smalling to a David Silva corner and power his header past David de Gea.
Sir Alex Ferguson had opted for an experienced line-up but United rarely threatened Joe Hart's goal and City looked likeliest to score in the second half.
Another goal was not forthcoming and it was an agonising final few minutes for the home fans as City held on to secure a potentially decisive victory.
Roberto Mancini's men now lead the title race by virtue of their superior goal difference, and it promises to be a fascinating fortnight with two games left to play for each side.
Sluggish
Although the team sheets indicated Ferguson had adopted a cautious approach and Mancini a more attack-minded one, in fact the opening exchanges provided an alternate view.
With his midfield reinforced by the introduction of Park Ji-sung to a Premier League starting line-up for the first-time since January, Ferguson's side quickly got into their stride and looked capable of carving out a decent opportunity or two.
However, Nani wasted their clearest opportunity when he ignored Phil Jones' overlapping burst and let fly from 35 yards with a shot that was hopelessly off-target.
City, meanwhile, began sluggishly, their midfield seemingly incapable of stringing a succession of passes together with any regularity.
Samir Nasri was the man who sparked them into life with a couple of mazy dribbles as the hosts started to get near the byline, which always gives defences cause for concern.
Sergio Aguero screwed a volley wide, then Pablo Zabaleta seized on an opportunity he would have been better leaving for Nasri and his shot rolled through to De Gea.
After all the hype, it was hardly a classic, although as the clock ticked down towards half-time, the United camp presumably reflected they were quite happy at that.
So, to go behind in stoppage time in such orthodox fashion would have been particularly galling for the visitors.
De Gea's frailties under the high ball are well known by now. When David Silva curled over the second of successive corners, a stronger, more confident goalkeeper might have come to punch. Instead, he left it to his defenders.
Smalling, like Park, making his first start since January after Jonny Evans was ruled out through injury, momentarily lost Kompany on their run from the edge of the box and was still marginally out of position when the Belgian rose to power home from six yards.
It was a devastating goal for United to lose as there had been no obvious indication they were likely to score.
Wayne Rooney looked particularly out of sorts, isolated up front and generally unhappy with the buffeting he was receiving, which had only drawn one yellow card for Kompany.
Momentum
The second half was only 12 minutes old when Ferguson offered his star man some badly-needed support, replacing Park with Welbeck.
Immediately before the change, though, United might have found themselves
