Manchester City are to lodge an official complaint after striker Mario Balotelli allegedly suffered racial abuse from the crowd during Thursday night's win at Porto.
The club informed UEFA's matchday delegate of their intention to complain after the 2-1 UEFA Europa League success at the Estadio Dragao and will follow it up in writing on Friday.
Balotelli complained about being subjected to abuse first, with midfielder Yaya Toure backing up his claim.
Although manager Roberto Mancini did not hear the abuse, the striker has told a club official he heard abusive chanting during the game.
Reports circulated during the match that Balotelli and Toure were subjected to monkey noises.
When asked about it after the game, Mancini said he did not hear it - but Toure told Sky Sports News that he "heard something".
"That's why we all like the Premier League, because it never happens there," he said.
"Maybe in foreign countries they don't expect black players.
"I think in future it will be okay, they will change their minds and the game will become more open
"Football is football and the fans come to enjoy the game, and we don't want things like this to happen.
"Mario is now able to control things like this and that is very important for the club."