Man Utd 4-2 Man City.
Manchester United produced a display of maturity and came out as victors in the 169th Manchester derby as they turned the game around in ruthless fashion.
While the City players decided that kicking their rivals was the best route to a win, United kept their heads and proved that they have a new found resilience and a collective team spirit about them.
City had won the last four derby games but have been in free fall over the last two months and were ripe for the picking by United.
Louis van Gaal made only one change from last week's victory over Aston Villa as Chris Smalling recovered from his illness and replaced Marcos Rojo in the centre of defence.
Manchester United: De Gea, Valencia, Smalling, Jones, Blind, Carrick, Fellaini, Herrera, Mata, Young and Rooney.
Subs: Valdes, Rafael, Rojo, McNair, Januzaj, Di Maria and Falcao.
Once again no starting place for Di Maria or Falcao as Van Gaal decided not to change a winning formula.
City kicked off the match in front of a full and very vocal Old Trafford crowd.
In the first minute, Clichy went hard into Mata on the touchline and luckily there was no serious damage, but it showed City's intent. From the resulting free-kick Rooney was almost in on goal but keeper Hart rushed off his line to smother the ball.
Manchester United are the form team so it was a surprise to see the Red Devils make the most-nervy start of the two under the rain at Old Trafford.
A long ball over the top of United's defence saw Aguero through on goal and as he bore down David de Gea produced an excellent stop to thwart the Argentinian and stop a certain goal.
However, City continued to press and in the seventh minute they cut the United defence open too easily. David Silva had all the time in the world to pick out Aguero who tapped the ball into an empty net.
First blood City. The most important question for van Gaal had to be where were his defenders?
A bad start from the home side but early enough to rectify the situation.
In the first ten minutes, United struggled to get a hold of the ball and City were finding it all too easy to control the play.
12 minutes in and Young was brought down as he attacked down the right. The free-kick from Mata came to nothing, but it was a sign that United were getting their game together.
Two minutes later and United scored to level the match. It was Ashley Young who came up with the crucial equaliser, but it was started from a David de Gea clearance.
As the keeper hoofed the ball down the field it was headed on by Fellaini and collected on the left by Ander Hererra who whipped over a cross that the City defence failed to clear under pressure. Young was in the right place and the winger reacted first to spin and stab the ball home.
1-1 and game on.
What a lively start to the game as both teams scored goals from defensive mistakes. I have never seen de Gea have to come outside his box to clear the ball as much as he had to in that mad twenty minute spell.
Milner received the first booking of the match on 24 minutes after he hauled back Herrera. Young took the resulting free-kick and picked out Fellaini inside the area, unfortunately, his header down found no one.
In the 27th minute, United took a well-deserved lead. The crowd witnessed great skill from Mata in the middle of the park as he brilliantly made room for himself and sprayed a pass to the left.
The ball came to Young who produced a back heel to set up Blind who returned the pass to Young allowing the winger the time needed to deliver a delightful cross to the far post where Fellaini powered home a header to put the Red Devils ahead.
A great team goal that showed the confidence pulsing through side and one that lifted the roof off Old Trafford.
Thirty minutes in and United had gained control of the match but City still threatened up front from the running of Aguero.
On the half hour, there was yet another booking for City as Silva brought down Mata. United's two Spaniards were certainly getting worked over in the first half.
David de Gea had to be on his toes as his defenders continually made him rush out and clear his lines after they continued to leave him unguarded at the back.
In the 42nd minute, Antonia Valencia brilliantly tracked Aguero all the way to the touchline to deny the attacker any chance on goal and even won a goal kick. In that instant, Valencia showed how much he has improved as a defender.
Just before the break the City captain Kompany should have been sent off for a terrible high footed challenge on Daley Blind but the referee Clattenburg, after consulting with his assistant, only produced a yellow.
A bad decision by the referee who had recently shown Kompany a red card on international duty along with the two dismissals of Blackett and Shaw earlier in the season.
United should have done better with the last chance of the half, but they couldn't get that vital third goal as both Rooney and Fellaini tried to create clear chances.
Half-time and after a nervy start United found their composure to make a fight of it and fully deserved the lead they enjoyed. However, the problems at the back had resurfaced again with Phil Jones being guilty of not man marking when City attacked, something that they would have to be aware of in the second half.
City were lucky to go in with eleven players as Vincent Kompany should have seen red for his challenge on Blind who in turn was lucky not to have a serious ankle injury.
Ashley Young was once again producing a sterling display down the left with a goal and an assist.
United started the second half attacking the Stretford End with no changes to the side. City, however, made a change by craftily dragging off Kompany so he wouldn't see red.
There was a cautious start to the half as both sides were wary of giving away possession too easily after the defensive mistakes in the first 45 minutes.
After 51 minutes, Mata was brought down yet again on the edge of the area. Mata and Rooney sized up the options and it was Rooney who fired a shot over the wall which Hart did well to reach.
From the resulting save all mayhem broke loose as the ball fell to Michael Carrick in the box, but his shot was blocked by a combination of Hart and an unsuspecting Fellaini.
Two minutes later Martin Demichelis went down clutching his face after seemingly being struck by one of Fellaini's elbow, but as soon as the referee approaches him and tells him to get up, he leaps to his feet in disgust. Either that was blatant simulation or it was the fastest recovery to top all recoveries. Pure comedy.
The thing that was pleasing was how the United players remained calm while most of the City players harassed Clattenburg. The blues showed their true colours and frustration that things were not going their way as their season was taking a turn for the worse.
58 minutes in and Valencia broke down the right he found Mata then the ball was eventually crossed into Ashley Young who headed weakly towards goal, but he was adjudged to be offside anyway.
United gave away a foul on Milner in a dangerous area after which he was immediately replaced by Nasri. From the resulting free-kick there was Fellaini helping out in defence to clear.
In the 67th minute United made it 3-1. Scored by Juan Mata but made by a wonderful through ball by Wayne Rooney. The Spaniard still had a lot do as he was one on one with Joe Hart.
But there was only going to be one outcome as Mata slipped the ball through the keeper’s legs to give United breathing space.
A brilliant goal by the in-form Mata who is just oozing with confidence lately.
73rd minute and it was 4-1 to United and game over. Chris Smalling ventured forward for a Young free-kick and as City's defence slept there was Chris Smalling to head home completely unmarked.
The ground erupted with pure joy as the fans wildly celebrated the goal and what was to be a well-deserved win.
Shortly after the goal Phil Jones was replaced by Marcos Rojo. Both Smalling and Jones had played well at the back together after a shaky start. But they don't exactly fill you with confidence and it was a relief to see Rojo at the back for the remainder of the game.
As the last twenty minutes came it was all United and they even had the luxury of bringing on Di Maria for the last ten minutes for the impressive Juan Mata, who fully deserved the standing ovation he received from the adoring faithful.
That was followed in the 82nd minute by the entrance of Radamel Falcao for Fellaini who also enjoyed warm applause from the crowd after his all-round performance.
One minute remained on the clock and United were down to ten men with Michael Carrick limping off and United had made all their changes when City pulled a goal back through Aguero who shot from close range and despite de Gea being able to push it on to the post it crept in.
A consolation goal for the visitors but it showed you can never switch off with Aguero in the side.
The final score was 4-2 to United and a win that was thoroughly deserved in a hard fought match in which City started the better of the two sides. To their immense credit, United picked themselves up and proved their new found resolve by keeping their heads and playing some great attacking football.
A number of United players impressed during the match, but special mention has to go to Fellaini, who is proving unplayable in his current role. Mata had another brilliant match and linked well with midfield and attack. Rooney never stopped running up front and created the Mata goal.
But the man of the match had to be Ashley Young, who is having a splendid season and fully deserves the plaudits he is receiving. Chipping in with a goal and two assists he is playing so well that Di Maria is keeping the bench warm.
That was United's sixth straight win in the league and sets up a mouth-watering clash against Chelsea next weekend at Stamford Bridge.
Runners up spot has to be the main aim now as Champions League qualification has all but been guaranteed after today's great win.
Let's hope United can keep the good run going and add Chelsea's scalp to the so called big teams that have fallen before us recently.