A man arrested over allegations of racist abuse against Manchester United players during Saturday's derby match has been released on bail.
The 41-year-old Manchester City fan was held on suspicion of a racially aggravated public order on Sunday.
A video had been circulated on social media of a man making monkey gestures and sounds towards United players.
Greater Manchester Police (GMP) said the man had been released pending further investigations.
The racist abuse allegedly happened at Manchester City's Etihad Stadium as United midfielder Fred went to take a corner and appeared to be hit by an object hurled from the crowd.
After the match, the 26-year-old Brazilian said: "On the field, I didn't see anything. I saw it only in the locker room afterwards. The guys showed me. [A man] even threw a lighter and it hit me."
United boss Ole Gunnar Solskjaer said the apparent behaviour of the supporter caught on camera was "unacceptable".
In a statement, Manchester City said after the game: "The club operates a zero-tolerance policy regarding discrimination of any kind, and anyone found guilty of racial abuse will be banned from the club for life."
The Football Association also said it would investigate the incident, while the Premier League said it "will not tolerate discrimination in any form".
Fred said the alleged incidents on Saturday showed "we are still in a backward society".
United won the match 2-1 after goals from Marcus Rashford and Anthony Martial.