Fans of Liverpool and Manchester United have been given a stark warning before their teams' Champions League games in Moscow next week.
Supporters travelling to the Russian city have been warned that there will be a "visible police presence" on the streets to prevent any violence.
Liverpool are playing Spartak Moscow on Tuesday (September 26) while United play CSKA a day later.
There have been concerns about potential conflict between fans of the two English clubs, as well as the presence of Russian hooligans.
United have also warned fans not to wear their colours on the streets of Moscow, and not to go out alone.
The security alerts will only fuel worries about Russia's suitability as a venue for top-level football, given the country is due to host the World Cup next year.
Russian hooligans earned global shame when they clashed with English fans a last summer's European Championship in France, causing huge violence in the city of Marseille.