Police investigating a racist tweet sent during Sunday's stormy Manchester derby have arrested a 15-year-old boy.
The teenager was held on suspicion of a racially aggravated public order offence, Greater Manchester Police said.
An investigation was launched after a message was directed at a Manchester United player.
The boy has been bailed pending further inquiries.
Police made nine arrests in all as tempers among rival fans boiled over and officers have appealed for anyone with information about hooligans throwing coins to get in touch.
Nine men will appear in court in January.