Black players could boycott the 2018 World Cup in Russia if the country does not tackle racism in the stands, according to Manchester City's Ivory Coast midfielder Yaya Toure.
Toure, whose allegations that he suffered racist abuse during Wednesday's 2-1 Champions League victory at CSKA Moscow have prompted UEFA to open disciplinary proceedings against the club, said FIFA and Russian authorities needed to act.
"It's very important," British media quoted him as saying on Friday. "Otherwise we are not confident coming to the World Cup in Russia. We don't come."
But Sepp Blatter, president of world soccer's governing body FIFA, said a boycott would not be a deterrent against racism.
"I think we should never speak about a boycott of the World Cup," Blatter told reporters in Oxford, England.
"We should fight against racism but the boycott would not be a weapon against racism."
The idea of a boycott did not sit well with some Premier League managers and Chelsea's Jose Mourinho said the enjoyment of the majority should not be ruined by the actions of the minority.
"A huge percentage of the people that go to football stadiums are people who respect the differences and respect everybody, and they are more important than the small groups that express themselves in a negative way," he told a news conference on Friday.
"The history of football was made by many races. Let's fight the thousands but let's give to the billions what the billions want, and that is the best football with the best players from all over the world, whatever their race."
Arsenal manager Arsene Wenger said European soccer's governing body UEFA needed to complete its investigation before there could be any talk of a boycott.
"To go as extreme as you suggested (boycott), it's a bit early to do that because it's not proven what happened," he told a news conference.
"I believe that Russia itself has to fight against that and, of course, you want everybody to be active on that."
The episode has been embarrassing for UEFA during its 'Football Against Racism in Europe Action Week'.
Europe's governing body has been criticized by world players' union FIFPro for failing to enforce its own guidelines, under which match officials have the power to stop and abandon games in case of a serious incident.
On Friday, UEFA president Michel Platini ordered an internal inquiry into why Romanian referee Ovidiu Hategan and his assistants did not follow the guidelines.
CSKA have denied Toure's allegation of racism, saying they were "surprised and disappointed" by it.
Toure, who speaks Russian after spending two years playing in Ukraine for Metalurg Donetsk, said the abuse he experienced in Moscow was worse than anything he encountered in Ukraine.
"We had some racism in Ukraine, but maybe only one, two or three people, not in groups like that (on Wednesday)," he said.