Russia manager Guus Hiddink blamed schoolboy defensive errors for his side's 4-1 Group D defeat to Spain.
Hiddink's side looked good going forward but struggled at the back, and the Dutchman has demanded much-improved performances against Greece and Sweden in their remaining group encounters.
He said: "If you see the second goal, if you see the fourth goal, some school teams don't make those errors.
"It is not the members of the defence, it is a matter of the whole team, knowing when the fire starts and knowing when to be firemen. To be honest I was rather angry at half-time because of this naive behaviour.
"At the end of the game in the locker room I said this is a tournament of three games.
"We have to learn within hours not to be naive. If we can manage to learn fast we have chances in the other two games.
"We will see how Spain react when they get more opposition, against a team that know the law of international competition. We helped them too much today."