Tomas Rosicky's injured Achilles is improving but the Czech Republic captain said he would wait until a fitness test before Saturday's match against Poland to decide if he could play.
The playmaker will not train on Friday but remains hopeful he will be ready for their final Group A match.
"It is getting better and we decided I will not train tonight and we will see tomorrow," Rosicky told reporters. "This is not the end. I'm not telling myself that."
Russia top Group A with four points from the Czech Republic on three, with co-hosts Poland on two and Greece who have one.
A win for either Poland or the Czech Republic guarantees a quarter-final spot, although a draw would be enough for the Czechs if Greece do not beat Russia in Warsaw.
If Rosicky is ruled out coach Michal Bilek may look to Daniel Kolar who replaced his captain in the second half against Greece but was not as effective with the Czechs lacking any attacking threat.
There was better injury news regarding goalkeeper Petr Cech who has said he will play despite suffering with a sore shoulder that has limited his pre-match training.
Asked if would tell his players the score in Russia-Greece match being played simultaneously he said: "I don't know if I'll tell my players or not. If I do it will be late in the game."comments