A last gasp Robin van Persie goal sent Manchester United six points clear of their City rivals with a famous away win at the Etihad back in December.
The season before, City had beaten their title rivals both home and away to secure the Premier League title but it was Sir Alex Ferguson's side who dealt the heavy psychological blow this time round. Wayne Rooney had earlier put his side into a commanding 2-0 lead going into half time and the score might well have been 3-0 had Ashley Young not incorrectly had a goal chalked off.
The decision to rule the goal out through an offside decision nearly cost United dear as City roared back into the game in a much different second half in which a Yaya Toure strike and a late Zabaleta equalizer seemed to keep the gap at the top at three points.
Yet Robin van Persie had other ideas when he stepped up to take a free kick in the 90th minute, and as the ball deflected off the wall and wrong footed Joe Hart, it would be United who took the three points and add to their lead at the top of the table.
Ugly scenes followed as Rio Ferdinand was hit in the eye by a coin tossed from the crowd while Hart had to restrain a pitch invader as chaos ensued.