Police investigating a racist tweet sent during Sunday's stormy Manchester derby have arrested a 15-year-old boy.
The teenager was held on Monday night on suspicion of a racially aggravated public order offence and has been bailed pending further inquiries, Greater Manchester Police said.
An investigation was launched after a message was directed at a Manchester United player.
United and England defender Rio Ferdinand was left with a cut to his left eyebrow after being hit by a 2p coin while celebrating his team's last-gasp winning goal at the Etihad Stadium.
City fan Matthew Stott, 21, had to be restrained by goalkeeper Joe Hart as he tried to confront Ferdinand, and was arrested.
Police made nine arrests in all - with those men to appear in court in January - as tempers among rival fans boiled over and officers have appealed for anyone with information about hooligans throwing coins to get in touch.
Information from the Press Association was used in this report