text: Louis van Gaal blamed himself for Manchester United finishing the game with 10 men, using all his substitutes before Michael Carrick came off as a precaution with a tight calf. The United boss said: ‘It was of course an error from me that I give too much minutes to my substitutes. It is not so wise. 'Some players didn’t know that we were playing with 10 men because the crowd were yelling and it was difficult to get the message to them.’ Manchester United manager Louis van Gaal (right) celebrates victory with Ander Herrera at full-time . An injured Michael Carrick walks along the touchline after coming off as a precaution with a tight calf . Aguero's quick-fire ton . It will come as little consolation to Sergio Aguero that he reached the 100-goal mark faster than any player in Manchester City’s history with his double at Old Trafford. The striker has had to wait for that honour, however, with his first goal ending a barren run stretching back eight hours and 39 minutes to the defeat home to Barcelona in February. Sergio Aguero (centre) celebrates after scoring the opening goal at Old Trafford on Sunday afternoon . It was Aguero's first goal since he scored for City against Barcelona at the Etihad back in February . Milner goes off in a strop . James Milner's reaction to being substituted as he waited to come back on following treatment after a reckless challenge from Phil Jones does not augur well for the England winger ending his contract stalemate. Milner was standing on the touchline when he discovered that he was being replaced by Samir Nasri, and hurled an energy pouch to the floor in frustration before trudging back to the dugout. Manchester City's James Milner goes off with an injury during Sunday's Premier League derby . United felt that Martin Demichelis overreacted when he was caught in the face by a flailing arm from Marouane Fellaini in the second half, but the Belgian does have a rather patchy track record on that score. Pablo Zabaleta was furious that Fellaini was only given a yellow card at Old Trafford last season when he felt he was the victim of a blatant elbow from the United man. Manchester City's Martin Demichelis (centre) protests to referee Mark Clattenburg as United players look on .
target: United finished the game with 10 men after Michael Carrick came off .
  Sergio Aguero reached the 100-goal mark faster than any other City player .
  James Milner hurled an energy pouch to the floor in frustration after he was replaced by Samir Nasri .
  United felt that Martin Demichelis overreacted when caught by a flailing arm from Marouane Fellaini .