Manchester United defender Rio Ferdinand has told Manchester City executive Patrick Vieira to concentrate on his own team.
Vieira stated earlier on Wednesday that he believes that United get preferential treatment from referees at Old Trafford, but Ferdinand has told the Frenchman to "let it go".
"Why is Viera so concerned with Man Utd...2 comments in a week or so...c'mon maaaaaan let it go!" Ferdinand tweeted.
United are top of the Premier League with eight games to play.