Coach Fernando Santos insists he has paid no attention to the Czech Republic's heavy defeat to Russia during Greece's preparations for their Group A meeting in Wroclaw.
The Czechs sit bottom of the group after being thoroughly outplayed by an impressive Russia side on Friday.
Greece, meanwhile, played out a 1-1 draw with co-hosts Poland and know that victory tomorrow would see them dump the Czechs out of the tournament.
But Santos knows Michal Bilek's side still pose a major threat to the Greeks despite their terrible start.
"It changes nothing that they lost against Russia. They're compact, and have a lot of pace," he told a press conference.
"In the game against Russia, the Czechs had the upper hand in the opening 20-25 minutes. I think they showed their qualities, despite their 4-1 loss."
Santos faces a selection headache when it comes to picking his starting XI at the Municipal Stadium.
The Greeks drew 1-1 with co-hosts Poland on Friday, but the result came at a cost.
Defender Sokratis Papastathopoulos is suspended after his harsh first-half sending-off in Warsaw, while Avraam Papadopoulos suffered a torn cruciate ligament.
Kyriakos Papadopoulos is set to come into defence but midfielder Giorgos Fotakis is another absentee with a thigh injury.
While he has problems in defence, Santos is backing his side to take the game to the Czechs, after a circumspect showing against the Poles.
He said: "What we must focus on are our attacking qualities. We defended very well, and also managed to attack in a very good way. This is modern football.
"It's something we didn't do in the first half against Poland, but did in the second. When our players understood that they could do both, their self-confidence improved, and I think you'll see this in this game."
Bilek, meanwhile, is set to make changes to his starting line-up, with Michal Kadlec set to revert to centre-half after struggling at left-back against the Russians and David Limbersky likely to start. Striker Milan Baros might also miss out.
And goalkeeper Petr Cech has warned the Greeks they will face a fired-up opponent.
The Chelsea player told uefa.com: "I think the anger (of defeat) has changed into determination. Determination to fix the bad start we had in the tournament.
"We felt the disappointment immediately afterwards, for sure. We did not succeed in any way in that first match, but we know we have another 180 minutes to play to allow us to qualify for the quarter-finals. So we're determined to do just that."