Manchester United extended their Premiership lead to nine points with a win over neighbours Manchester City.
Wayne Rooney celebrates putting Man Utd ahead in the derby
Wayne Rooney turned in Cristiano Ronaldo's cross after five minutes and Louis Saha bundled home a second from a Gabriel Heinze cross on half-time.
City lost injured keeper Nicky Weaver, but Hatem Trabelsi pulled one back with a rising drive after 73 minutes.
Ronaldo's late strike sealed the win, before City's Bernardo Corradi was sent off for diving.
City needed to make a solid start against their rivals - but United were in front after only five minutes.
Ronaldo's cross took a slight deflection of Sylvain Distin, but Rooney never broke stride to score with a perfect side-foot finish.
Stuart Pearce's side responded to the early setback with real spirit, and their outstanding youngster Micah Richards was inches away from an equaliser after 19 minutes, but he headed just wide under pressure from Rio Ferdinand.
Georgios Samaras then brought a fine save from Edwin van der Sar with a crisp volley.
As City attempted to battle their way into the game, Samaras stopped a goal-bound header from Richards virtually on the line, but was unable to turn it past Van der Sar.
City's frustration increased when United doubled their advantage on the stroke of half-time - a cruel reflection of the first-half play.
Trabelsi carelessly played Dunne into trouble, and when he was robbed by Rooney, Gabriel Heinze crossed for Saha to bundle past Weaver.
Weaver sustained a knee injury in the collision and was replaced at half-time by Andreas Isaksson, the Sweden keeper making his debut after a £2m summer move from Rennes.
Stephen Ireland also came on for the injured Claudio Reyna, and he swiftly brought another important save from Van der Sar.
Saha missed a glorious chance to add United's third after 52 minutes, but he shot wildly over the top after Isaksson could only block Rooney's shot.
Isaksson then turned over a rising drive from Giggs as United threatened to take advantage of City's need to push forward.
Uniyed had not been at their best, but Rooney was a constant threat, forcing a diving save from Isaksson with an instant left-foot shot on the run.
Sir Alex Ferguson made a tactical switch after 66 minutes, replacing Saha with John O'Shea, who was pushed into a protective role in front of the back four.
Isaksson was in action again two minutes later as United started to produce flashes of their trademark passing game, denying Rooney at point-blank range from Giggs' cross.
But City were refusing to give up and pulled a goal back in spectacular fashion, Trabelsi shooting high past Van der Sar with an angled drive from 18 yards.
Richards was injured in the build up and was stretchered away, to be replaced by Damarcus Beasley.
City's hopes of a comeback were snuffed out six minutes from time when Dunne missed Rooney's cross and Ronaldo turned home.
And to round off City's misery striker Corradi, who had already been booked, was sent off by referee Graham Poll after a ridiculous and unnecessary dive.
Man Utd boss Sir Alex Ferguson:
"We have had a tough spell. I am sure people thought we might drop something this week.
"But, credit to the players, they've done well even though fatigue was beginning to show a bit at the end.
"We should have put the game to bed in the second half but unfortunately we didn't take our chances and we could have suffered because of it."
Man City boss Stuart Pearce on Bernardo Corradi's sending-off:
"I have no complaints about the sending-off.
"Bernardo went down a little bit too easily and I am not like the other 19 managers, who would sit here and give you a load of cock and bull about it.
"I would prefer him to stay on his feet and I intend to speak to him about it this week. Hopefully then, he will stay on his feet."
Man Utd: Van der Sar, Neville, Ferdinand, Vidic, Heinze, Ronaldo, Carrick, Scholes, Giggs, Rooney, Saha (O'Shea 66).
Subs Not Used: Kuszczak, Solskjaer, Fletcher, Silvestre.
Goals: Rooney 6, Saha 45, Ronaldo 84.
Man City: Weaver (Isaksson 46), Richards (Beasley 76), Dunne, Distin, Thatcher, Trabelsi, Reyna (Ireland 46), Barton, Vassell, Corradi, Samaras.
Subs Not Used: Dickov, Onuoha.
Sent Off: Corradi (90).
Booked: Thatcher, Reyna, Corradi.
Goals: Trabelsi 72.
Ref: G Poll (Hertfordshire).