CRISTIANO Ronaldo's powerful header 11 minutes from time sent Portugal into the Euro 2012 semi-finals with a deserved 1-0 victory over the Czech Republic last night.

The world's most expensive player hit the woodwork twice on an initially frustrating evening but crowned Portugal's dominant second-half performance with his third goal of the tournament, nodding a Joao Moutinho cross into the net.

It was an impressive display from the Portuguese who were appearing in their fifth Euro Championship quarterfinal in a row and will play Spain or France in the last four.

The Czechs made a lively start inspired by the clever prompting of Petr Jiracek and Portugal took time to settle.

Their simple gameplan was based around getting the ball to captain Ronaldo at every opportunity and he openly vented his frustration when team-mates failed to pick him out.

Ronaldo failed to connect properly with an overhead kick to the delight of the Czech fans, smashed a 35m free kick well wide and just before halftime struck the post after a brilliant turn and firm shot.

Portugal's Nani and Miguel Veloso were booked as tempers frayed and they suffered another blow when striker Helder Postiga was carried off injured just before halftime and replaced by Hugo Almeida.

Almeida missed a great chance to open the scoring 19 minutes into the second half when he wastefully headed Raul Meireles's perfect cross over the bar.

Another long-range Ronaldo free kick grazed the outside of the post and the Real Madrid forward then lashed a half-volley over the bar.

Portugal were dominating and Nani forced Petr Cech into a sprawling save before Almeida was adjudged offside when he nodded Nani's cross into the net.

The Czechs earned a brief respite following a brilliant surging run down the left by Vaclav Pilar but Portugal hit back when Moutinho's swerving drive was tipped over by Cech and Nani's shot was saved after good work by Meireles.

The match appeared to be drifting towards extra time when Portugal picked another hole on the left side of the Czech defence and Ronaldo stole in to provide an emphatic finish by heading the ball into the ground with the bounce taking it high into the net beyond Cech.

Ronaldo showed the same kind of sparkle that saw the Portugal captain dominate play and claim a brace in his team's 2-1 defeat of the Netherlands last Sunday - goals he had dedicated to his son, who turned two the same day.

So often maligned for failing to recapture his Real Madrid form when wearing the Portugal shirt, Ronaldo's 79th-minute header took his Euro 2012 tally to three, making him joint top scorer with Germany's Mario Gomez - plus Russia's Alan Dzagoev and Croatia's Mario Mandzukic, whose teams failed to advance from the group stage.

A divisive figure around whom Portugal are often accused of creating a cult of personality, Ronaldo won the loudest cheer from his fans in Warsaw's National Stadium when the announcer reeled off each squad, but earned catcalls from Czech supporters when he stepped up to take free kicks.

Reuters, Sapa-AFP