Police in Warsaw have pledged to protect football fans to avoid a repeat night on Saturday of the trouble that marred a Euro 2012 match between Poland and Russia on Tuesday.
Russia play Greece in the Polish capital and 20,000 Russians and 4000 Greeks are expected to attend. Warsaw's 100,000-capacity fanzone is expected to be full.
At the same time, Poland will play the Czech Republic in Wroclaw.
Police are under pressure to prevent any trouble, after being criticised for acting too slowly when Polish hooligans attacked Russian fans.
Croatia was fined 25,000 euros after fans threw flares and missiles on to the pitch during a match against Ireland in Poznan, and fines have been imposed on Germany and Portugal for similar offences.
Russia was fined 120,000 euros over the setting off of fireworks and display of "illicit banners" during a match against the Czech Republic.
Russia lead the group with four points with the Czechs on three, Poland on two and Greece on one.