Rosicky, whose precise passing and ability to take on defenders makes the Czech side tick, missed the second half of Tuesday's 2-1 Group A victory over Greece due to the injury.
Team officials are sweating on whether the diminutive midfielder will be ready for the clash with the co-hosts Poland in which a win would guarantee a quarter-final spot.
"Petr Cech is doing light training today and Tomas Rosicky told me his Achilles is not as painful as it was yesterday," Czech spokesman Jaroslav Kolar said on Thursday.
"He is in the dressing room undergoing treatment."
Rosicky said on Wednesday he could barely stand on his injured foot but was still hoping to play in his team's final Group A match. Team doctors gave him a 75 percent chance.
Cech, whose blunder led to Greece's goal, played the whole game despite his shoulder problem but it has since improved and the keeper said he would be ready to play.
"I will be fine," Cech said. "I will 100 percent be ready for the match."
