Moscow: Cristiano Ronaldo's diving header was good enough for a 1-0 win that put Portugal in the Euro 2012 semifinals at the Czech Republic's expense.
Portugal will face either Spain or France in the semifinal.
Ronaldo dominated the game as Portugal's most important attacker and the most creative player in an otherwise cagey match.
After missing a string of chances and hitting the woodwork twice, Ronaldo scored the crucial goal on 80 minutes, latching onto Joao Moutinho's cross with a diving header that bounced above goalkeeper Petr Cech's outstretched palms and into the net.
With the Czechs' defense breached, they struggled to create chances for an equaliser as Portugal kept control of the ball to deny the Czechs possession and choke off any possibility of attack in the dying minutes.
Czech Republic: Petr Cech, Theodor Gebre Selassie, Michal Kadlec, Tomas Sivok, David Limbersky, Jaroslav Plasil, Vaclav Pilar, Tomas Hubschman (Tomas Pekhart 86), Vladimir Darida (Jan Rezek 61) Petr Jiracek, Milan Baros.
Portugal: Rui Patricio, Pepe, Joao Pereira, Bruno Alves, Fabio Coentrao, Raul Meireles (Rolando 88), Miguel Veloso, Joao Moutinho, Helder Postiga (Hugo Alemeida), Cristiano Ronaldo, Nani (Custodio 84).