Arsene Wenger has said that the gap in points between the teams at the top of the Premier League can be deceiving.
The manager told the club's official website: "We have a game that is based on collective expression so it's difficult to compare man-to-man. At the moment, we are 20 points behind and that is linked with our bad start to the season but mainly to the fact that against the big clubs, we did not do well.
"Then I can tell you that in Germany, Dortmund are 20 points behind Bayern Munich and they just beat Real Madrid 4-1. The same people that say 'you are 20 points behind' are the same that say Dortmund is the best team in Europe.
"Man City is for sure a very good side that can compete with Man United. They dropped some points this season that were unexpected and [Roberto] Mancini is right on his statement [that team are closer than the table suggests]. I agree completely with him and we have seen that again when they played against Man United."
United are 13 points clear at the top of the Premier League table.