Manchester City boss Pep Guardiola suggested that Bruno Fernandes' controversial goal in the 2-1 defeat against Manchester United would not have stood had it not been scored at Old Trafford.
The goal was initially ruled out because Marcus Rashford had strayed offside but was awarded because he had left the ball for Fernandes, who was onside, to shoot past Ederson.
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City's players argued that Rashford had interfered with play and Guardiola suggested afterwards the decision had been influenced by the home crowd.
"Rashford is offside, Bruno is not offside, the question is interference," Guardiola said. "When one player from 18-yard box shoots and one player is in front of the keeper but doesn't touch the ball, it is disallowed all the time.
"The situation and the decision is the referee's, the VAR, our defenders make a line [for Rashford], if we know it's Fernandes we don't make the line, we follow the action, and after the action the interference for [Ederson].
"This is the decision in this stadium with the referee and the VAR. Here he said not intervene in this stadium. What are we to do? Are we going to make a complaint? No. It sometimes happens on our side.
"The decision is they didn't believe Rashford was intervening in this stadium. This is Old Trafford, we have to play much better, like Anfield, we have to do better."
City have now lost back-to-back games after exiting the Carabao Cup at Southampton on Wednesday and have won four of their last eight in all competitions.
They next face Tottenham at the Etihad on Thursday and Guardiola wants his team to move on quickly from their derby disappointment.
"With Southampton I cannot defend but [today] we play good, I have a feeling we played better," Guardiola said. "But this is about results and the results are not as consistent as we had in the past, that is a reality, work on that, continue.
"I said to the players, don't waste energy thinking about what happened. From my experience when we start to talk a lot, I won't say we win or lose for this action [the offside].
"You waste energy thinking what happened in the past, you are in the next game and you take a break. The best we can do is analyse the things we've done good and what we can improve and focus on Spurs."