Violence has erupted at Euro 2012 as Russia prepares to play Poland.
Around 10 thousand Russian football fans are in Warsaw, antagonising 30 thousand Poland fans.
Sky's John Davis says several supporters have been injured.
He says the Polish interior minister has called it the greatest challenge for law and order forces in the capital.
The Russian fans on Russia Day want to march to the stadium.
There's a history of tension between the two countries.
Meanwhile the Czech Republic is still a chance of going through to the quarter-finals of Euro 2012 after a 2-1 win over Greece in their group A match.
The Czechs were thumped 4-1 in their first group game by Russia, and needed to win to stay in the tournament.
Photo: Poland fans at Euro 2012 (Getty Images)