Jose Mourinho was unable to name Paul Pogba in his starting line-up due to injury, which meant a place for Marouane Fellaini -- and Romelu Lukaku was welcomed back into the squad, having missed the past two matches, but only on the bench. Pep Guardiola, meanwhile, brought Aguero back into his team in place of midweek hat-trick hero Gabriel Jesus.
As has been commonplace in recent weeks, United started the game slowly, while City came racing out of the blocks -- and were a goal ahead after 12 minutes.
The hosts created an opening on the left as David Silva fed Raheem Sterling and the England international hit a cross which evaded everyone -- aside from Bernardo Silva who had tracked the flight of the ball and kept it in play at the back post. The ex-Monaco man then knocked it back into the box to his namesake David, who showed great composure to cut inside a slot past David De Gea.
Had the goal not been given, it is likely the referee would have awarded a penalty after Chris Smalling had pulled down Aguero.
City looked like they could cut through United at will down their left, with Benjamin Mendy, Sterling and David Silva combining well to make life difficult for makeshift right-back Ashley Young. However, they failed to carve out another real opening before half-time.
But they didn't need to wait long for a second as Aguero made it 2-0 just three minutes into the second half, powering past De Gea, who was beaten far too easily at his near post.
Mourinho reacted by sending Lukaku to warm up before calling upon him on 57 minutes and the Belgian immediately proved his worth as he was brought down by the on-rushing Ederson for a penalty, which Martial converted to give the visitors hope of another comeback victory at the Etihad.
However, Ilkay Gundogan took advantage of lax defending to finish a 44-pass move and make it 3-1 to hand City a first home derby victory in four years which sees them return to the top of the table.
United, meanwhile, stay eighth -- seven points adrift of Tottenham in fourth place.
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