Both finalists were drawn in Group A of the tournament, and played each other in the opening game, with Greece winning 2–1 in what BBC Sport labelled a "shock defeat" for the hosts.

[4] Their only other major tournament appearance was at the 1994 FIFA World Cup, in which they also failed to qualify for the knockouts, losing all of their group games.

[11] Their match against eventual finalists Greece was the tournament's opening fixture, played on 12 June 2004 at the Estádio do Dragão in Porto.

They doubled their lead in the second half when Cristiano Ronaldo, a substitute for Portugal, fouled Greek player Giourkas Seitaridis and Angelos Basinas scored with the resulting penalty.

Ronaldo scored for Portugal late in the game, but Greece held on for a victory which marked the first time in European Championship history that a host nation had lost in the opening match.

[14] They took an early lead in the 7th minute, when Deco sent the ball into the area and it was met by Maniche, who scored into the bottom corner of the Russian goal.

Jorge Andrade scored an own goal five minutes later, under pressure from the Netherlands' Ruud van Nistelrooy, but Portugal held on for a 2–1 win and a place in the final.

[25] Spain took the lead shortly before the half-hour mark through a low shot by Fernando Morientes, after Raúl had taken the ball from Greece's Michalis Kapsis on the edge of the penalty area.

[26] Raúl had a chance to make it 2–0 with a header in the second half, but it was Greece who scored the next goal, when Angelos Charisteas intercepted a long pass from Vasilios Tsiartas for the equaliser.

The match finished 1–1,[27] leaving Greece on 4 points and needing only a draw from their final group game to progress to the next round.

Greece suffered an early setback, when Dmitri Kirichenko opened the scoring for Russia after 67 seconds,[28] which until Euro 2024 was the fastest goal in the history of the European Championship.

Shortly before half-time, Zisis Vryzas scored a goal for Greece to reduce the deficit, but they could not find an equaliser and the game finished 2–1 to Russia.

[3][33] The Czech Republic had two early chances – a powerful volley by Tomáš Rosický which struck the crossbar and a shot by Marek Jankulovski, which Greek goalkeeper Antonios Nikopolidis saved.

The remainder of the match was described by Mark Chaplin for UEFA as a "tight contest between the Czechs' superior technique and Greece's industry and commitment", and despite chances for both sides, it remained 0–0 after 90 minutes.

[38][40] Phil McNulty of BBC Sport characterised the opening as Greece "[retreating] quickly into defence in typical style, leaving Portugal to take the early initiative".

[40] Portugal made several early runs towards the Greek goal, first through Pauleta, who lost the ball to a tackle by Zagorakis, and then through Ronaldo, Deco and Figo, but after 10 minutes neither side had had any serious opportunities to score in the opening.

[40] Greece almost scored two minutes later when Charisteas was in possession 10 yards (9 m) from goal following a Portuguese defensive error, Ricardo running off his line to save the toe-poked shot.

Portugal had an opportunity with a free kick taken by Figo on the edge of the Greek penalty area, but it was too high for Ronaldo's attempted header.

Miguel was replaced by Paulo Ferreira in the 41st minute, after sustaining an injury, then Basinas received a yellow card shortly before half-time for a deliberate handball as Ronaldo attempted to pass the ball to Figo.

[40] Journalist Matthew Gibbs of These Football Times later described the goal as "practically a carbon copy" of Greece's headed winners against France and the Czech Republic in the quarter-final and semi-final, opining that Portugal's defence should have prepared for it.

Shortly before the end, Figo took a shot on the turn from inside the Greek box, which went narrowly wide, and Andrade had an attempt with a header which went over the crossbar.

May cited Greece's record of never having previously won a match at a major event, as well as their pre-tournament odds, which were as long as 150–1 with some bookmakers.

[36][45] In 2020, Gibbs similarly labelled it the greatest upset in the tournament's history, writing "They entered this grand stage as underdogs but calling the final result a shock almost does them an injustice in reality.

[41] Writers in France's Le Parisien wrote that the Greeks were "heroes of modern mythology who entered into legend and broke the hearts of all of Portugal", and Spain's Marca commented on Greece's style of play, saying "all winners deserve to win and although the debate as to whether they played football or anti-football is valid, the only thing that matters here is winning".

Gérard Houllier, one of the decision-makers for the latter award, commented that "Throughout the tournament, as well as in the final against Portugal, he showed leadership quality and skill and technical ability as well as his character".

Alluding to construction delays for the upcoming Olympic Games in Athens, Prime Minister Kostas Karamanlis said "These boys taught us a lesson as to what Greeks can do when we really believe in something".