Manchester City manager Sven-Goran Eriksson believes that his side learnt lessons from their home defeat by Arsenal which helped them win 2-1 at Manchester United.
The Citizens were two goals to the good at Old Trafford and rarely looked like surrendering the lead against their city rivals.
Eriksson told the Daily Mirror: "The difference between our games against Arsenal and United was our approach.
"In the first 30 minutes against Arsenal we didn't disturb them. We only conceded three free-kicks and what's that against the likes of Fabregas?
"I'm not saying go out and kill them, but go out and disturb them at the very least, pull their shirts sometimes.
"But against United it was a completely different attitude and fighting spirit.
"What we did against United, we should have done a week ago against Arsenal. We learnt our lesson and went out and did a perfect job against them."