Pep Guardiola fears racism will never be eradicated from football, though says clubs, players, managers and authorities must continue to fight the problem.
The latest in a long line of examples of racism in the game occurred on Sunday, when Antonio Rudiger alleged he was abused during Chelsea's 2-0 Premier League win at Tottenham.
A Manchester City supporter was arrested after he was seen to be racially abusing Manchester United players this month.
Guardiola is concerned the issue will ever be stamped out in football or society in general, but it must be tackled on a daily basis.
"I don't think so. We have to fight but it will take time, a lot of time, to eradicate it," he told a news conference.
"I think it was a problem which has happened for decades, centuries. But now it’s visualised more because the media is more up front and close to the problem.
"I think it's happened a long time, we just have to fight again and again. The little kids, in the schools, on the streets."
Asked if he would support his players walking off the pitch should they receive racist abuse, Guardiola said: "Of course my players support the initiative and what happened you have to battle day by day.
"It's not about one club or one person. It's about the football world, one vision.
"It's a battle you have to fight in the schools, especially, in the families at home to try to make a better society in the future.
"It's a battle day by day. All of the initiatives we are going to support and have been supportive."
