A teenager has been arrested over a racist tweet sent to Manchester United's Rio Ferdinand.
Police held a 15-year-old suspect after an alleged offensive message was sent to the Man Utd defender and former England captain during the derby clash between United and City.
A Greater Manchester Police spokesman said: "An investigation was launched following a message directed at a Manchester United player.
"A 15-year-old boy was arrested on suspicion of a racially aggravated public order offence.
"He has been bailed pending further enquiries."
Alex Ferguson's men won a thrilling encounter 3-2 by snatching the decisive goal deep in extra time to strengthen their place at the top of the Premier League.
But ugly scenes marred celebrations by United players, when Ferdinand was struck by a coin thrown from the crowd. The FA was investigating.