Warsaw police pledged to protect tens of thousands of fans expected in the Polish capital on Saturday and to avoid a repeat of the violence that marred the Euro 2012 match between Poland and Russia this week, leading to almost 200 detentions.
Russia play Greece in Warsaw on Saturday evening and 20,000 Russians and 4,000 Greeks have tickets to the stadium. At the same time Poland face the Czech Republic in Wroclaw and Warsaw's 100,000-capacity fan zone is expected to be full.
Police are under pressure to halt violence immediately, after being criticised for acting too slowly when Polish hooligans set upon a group of Russian fans marching to the stadium on Tuesday, and when another group tried to break into the fan zone.
The skirmishes were an embarrassment for the Euro 2012 co-hosts, prompting talks between the Polish and Russian leaders and an apology by Warsaw authorities to foreign fans.
Russian President Vladimir Putin told Poland's Prime Minister Donald Tusk during a phone conversation on Wednesday that Warsaw bore "full responsibility" for the safety of fans, raising the stakes in events which have brought the nations' troubled relationship to the fore.
Thousands of Russians were on their way to Poland early on Saturday, streaming across land borders or arriving by plane.
"Smiling fans are welcome in Warsaw. But if we see others around like last time then we will detain them immediately," said Warsaw police spokesman Polish fan Maciej Kowalski.
Police were forced to fire tear gas and rubber bullets after crowds of masked and black-clad local hooligans attacked Russia supporters.
Poland's Gazeta Wyborcza daily quoted an unnamed city official as saying "Police are supposed to react faster to violence."
Kowalski said police had arrested another six individuals involved in Tuesday's clashes after they were identified by the public from video images, bringing the total to almost 200.
Among those detained were 24 Russians, two of whom were expelled from Poland on Friday after pleading guilty to fighting and invading the pitch during the 1-1 draw between Poland and Russia.
Russian soccer officials are also under pressure to keep their fans under control, especially at the stadium, after UEFA threatened to dock them six points in qualifying for the next European Championship if their fans step out of line again following earlier disturbances at the tournament.