UEFA says it will wait for reports from the match officials before it determines if a disciplinary case will be opened against CSKA Moscow for racist chanting.
Manchester City will make a formal complaint after Yaya Toure said he was targeted with monkey chants by the home fans during last night's Champions League tie.
A number of commentators also said they had heard the chanting audibly during last night's match.
Toure told the referee about the chanting during and after the game.
Referees have the power to stop game and ask for announcements to be made over the public address system.
Anti-racism group Kick It Out have called for referee Ovidiu Hategan to be banned for not stopping the game.
It is not the first time, fans of Russian clubs have been accused of discriminatory chants.