Robin van Persie's injury-time winner moved Manchester United six points ahead of neighbours Manchester City at the top of the Premier League table.
Wayne Rooney finished a quick break with a scuffed shot past home keeper Joe Hart to put United ahead.

Rooney swept in Rafael's cross to double their lead, before Yaya Toure steered in to set up a tense finale.
Pablo Zabaleta drilled in an equaliser, but Van Persie's deflected free-kick won the game for United.

The Dutchman's late intervention capped a dramatic derby packed full of incident and sparked pandemonium in the away end at the Etihad Stadium.

It was a huge relief for United, who were aggrieved that they were denied a three-goal advantage seconds before Toure's goal.

Ashley Young pounced to convert the rebound when Van Persie's rasping shot cannoned back off the inside of Hart's left-hand post, but he was flagged offside in a marginal decision.
 
Rooney has now scored 10 goals in Manchester derby matches, with the brace moving him above Sir Bobby Charlton as United's all-time leading marksman in the fixture.