Manchester City executive Patrick Vieira believes that Manchester United get an "advantage" from referees at Old Trafford.
The former Arsenal midfielder's comments come two days after Fulham's Danny Murphy was seemingly denied a clear penalty in Monday's encounter at United.
"When United play at home they get some advantage that other teams don't get. I think when you go to United, Madrid, Barcelona, or Milan, when the referees referee these kind of games, it's always difficult to go against these kind of teams," Vieira told BBC Sport.
"This is the way it is. It's something the teams who are used to winning get all the time, so we need to win games so we have this advantage in the future."
City trail United by three points at the top of the Premier League.
