Refereeing governing body Pro Ref has admitted the decision to let Erling Haaland’s Manchester derby-winning goal stand was a mistake.Haaland’s second-half strike proved decisive as Manchester City beat local rivals Manchester United 1-0 at Old Trafford – despite playing more than hour with ten men after another controversial call saw Phil Foden sent off for kicking out at Bruno Fernandes.The original decision to disallow Haaland’s goal was overturned by VARGettyThe goal was initially not given for offside before eventually being awarded after a lengthy VAR check that concluded Haaland had been played onside by the foot of Man United defender Patrick Dorgu.However, Enzo Fernandez appeared to be offside and interfering with play as the ball travelled across the box to Haaland.Pro Ref statement And Pro Ref has admitted on-field referee Michael Oliver should have been instructed to review the incident.A statement read: “Following the incident in the 60th minute of Sunday’s Premier League fixture between Manchester United and Manchester City at Old Trafford, we can provide clarification regarding Erling Haaland’s awarded goal.“The on-field decision was offside against Erling Haaland – that was checked by VAR and he was found to be in an onside position.“In the same attack, it was established that Enzo Fernandez did not play the ball and therefore that makes any offside offence subjective, however, on this occasion, the VAR did not recognise the likely impact of his position and should have recommended an on-field review.“Contact has been made with Manchester United this evening to acknowledge what we deem is an error of judgement. A review of the incident will take place.”Earlier, former Premier League referee Dermot Gallagher had told talkSPORT he ‘couldn’t believe it wasn’t offside’.Carrick voices frustrationAnd Man United boss Michael Carrick expressed ‘concern’ about the process of reviewing the offside call.Speaking to BBC Radio 5 Live, he said: “I’ve got a big concern if I’m honest because I think we put so many layers behind referees now – screens, more bodies, more offices to get decisions right, and the dangerous bit for me is how the rules are being interpreted. Carrick has questioned the interpretation of the offside ruleGetty“I’m really concerned about how the game is seen from that angle. He [Fernandez] has thrown himself with a full diving header. From one angle you are thinking if he has touched it or not. [Lisandro] Martinez has to react to that, it has a major impact on the whole action. “The line itself, I wasn’t convinced it was drawn in a great position. I’m staggered and a little bit worried and concerned that if that’s how it’s interpreted, we are in a bit of bother.”City maintain 100 per cent startVictory means Man City have made a perfect start to the Premier League season, winning four games out of four.Haaland, who is now the leading scorer in Premier League Manchester derbies with nine goals, is up to six goals in six matches in all competitions this term.Enzo Maresca‘s City are back in action on Thursday when they entertain Norwich in the third round of the Carabao Cup, before another home clash against Sunderland in the league on Sunday.United host Brighton in the Carabao Cup third round on Wednesday ahead of Sunday’s league trip to Fulham.