Victory would send the Poles through to the last eight but any other result would see them crash out of a tournament they are co-hosting along with Ukraine.
Mainz midfielder Polanski, who is an injury doubt for his country's final Group A game after suffering a bruised knee, said: "We know that we can do something special for our fans and the country.
"This is the most important game in my career. This whole tournament is extremely important.
"All the preparation, all the training, four weeks of preparation, we are here for five weeks in total, and we want to demonstrate that we can give everything.
"If we give 100% of ourselves, we will win definitely tomorrow."
Poland boss Franciszek Smuda knew exactly what it would take to progress following successive 1-1 draws with Greece and Russia.
He said: "First of all, we have to play good football. Secondly, we have to fight from the first to the last whistle."
As well as Polanski, Smuda has doubts over defender Damien Perquis and midfielder Dariusz Dudka.
He added: "If we had no problems with injuries, I would really like to use the same line-up as we had against Russia, but maybe those injuries will impact our decision and we'll have to make some changes."
Smuda's other major selection dilemma revolves around whether to recall Wojciech Szczesny in goal or keep faith with Przemyslaw Tyton, who saved a penalty after Szczesny was sent off against Greece.
Asked who his goalkeeper would be, Smuda joked: "Definitely not me. Whoever's between the posts.
"We have many question marks. We have some injuries. Tomorrow, we'll take the final decision."
Czech Republic had injury concerns of their own today but goalkeeper Petr Cech looked to have recovered from a shoulder problem after coming through training unscathed.
The same could not be said for captain Tomas Rosicky, who sat out the session with the Achilles injury that forced him off during Tuesday's 2-1 win over Greece.
Rosicky said: "It's getting better but we decided that I will not train tonight and we will wait until tomorrow."
The Arsenal midfielder played down fears his absence would have a devastating impact on his team-mates.
"What I'm feeling in the team is great hope, a great chance to go to the quarter-finals," he said.
"Of course, the guys are worried if I play or not.
"But we hope to go through. We've got a great opportunity here and we are aware of it, and we want to grab this chance and go through."
A draw should be enough for the Czechs to progress unless Greece manage to shock Russia in the other final group game.
Head coach Michal Bilek was not afraid for his side to be cast as the villains tomorrow.
"We want to go to the quarter-final," he said.
"Right now, it's one or the other and we will do our utmost to achieve this goal.
"Of course, we respect our opponent but we are not scared.
"We don't want to say goodbye to the Euros and we want to go through."