Manchester City midfielder Yaya Toure believes black players could boycott the 2018 World Cup unless Russia addresses racism in the stands.
Toure was the target of monkey chants during City's 2-1 victory over CSKA Moscow in the Champions League on Tuesday night.
UEFA have subsequently opened disciplinary proceedings against CSKA for the behaviour of their fans at the Luzhniki Stadium in Moscow, although the club denies the chants of their fans were racist.
The City skipper has now warned that black players may boycott the World Cup - which Russia will host for the first time in 2018 - unless the authorities take action.
"If we are not confident coming to the World Cup in Russia, we don't come," Toure said. "I don't know why it happens in football. I don't know why you don't get something like this in rugby or handball or any other sport.
"If UEFA don't take action it will continue. A couple of months ago my friend played with Milan and he had the same problem.
"I hope they do something - ban the club or the stadium for two years. The club may say they have to educate the fans but it's not enough. Too much is too much. We have to stop it now."
CSKA are adamant that Toure is mistaken. In a statement the club said: "Having carefully studied the video of the game, we found no racist insults from the fans of CSKA.
"On many occasions fans booed and whistled to put pressure on rival players but regardless of race. In particular this happened with Alvaro Negredo and Edin Dzeko. Why the Ivorian midfielder took it as being directed at him is not clear."