Cristiano Ronaldo scored the winner as Portugal advanced to the semi-finals of Euro 2012 with a 1-0 win over Czech Republic.

It was the Czechs who enjoyed an early spell of possession, with Jaroslav Plasil and Petr Jiracek particularly lively.

Portugal improved as the 10-minute mark approached, however, with the pace of Nani and Ronaldo causing the Czechs obvious discomfort.

Portugal's first real strike at goal came after 12 minutes when Joao Moutinho struck from distance. However, Petr Cech collected the danger.

It was the Czechs who continued to force the issue with a series of corners and Milan Baros might have turned home with an effort after 18 minutes.

Portugal's clearest opening came after 25 minutes when Nani fed Ronaldo, but Cech made a magnificent save. However, the skipper was ruled offside.

Ronaldo had another sighter after 33 minutes when he attempted an over-head kick inside the box, but it moved just wide of the target.

Ronaldo again came close moments later, but his long-range effort was always drifting away from the target.

Chances remained few and far between as the half developed, but Portugal had a penalty shout turned down on the stroke of the interval when Michal Kadlec felled Nani in the area.

Meanwhile, they came closer in first-half stoppage time when Ronaldo rattled the post from close range.

Portugal had an immediate chance to take the lead after the break when Fabio Coentrao found Hugo Almeida in the box, but somehow he headed over.

Portugal again came close when Ronaldo struck a free-kick from distance, but it thumped off the post for the second time.

That man again came close after 54 minutes, but once more he fired over the bar when he perhaps should have scored.

Nani tested Cech with an effort after 58 minutes, as Portugal continued to dominate the early stages of the second period.

Moutinho was next to test Cech after 65 minutes with a long-range effort, with the Czechs sinking deeper and deeper.

The goal eventually came after 79 minutes when Ronaldo met a Moutinho cross with a thumping header to send his country into the lead.

Joao Pereira might have made it two after 83 minutes, but Cech produced a fantastic save to push the ball to safety.

In truth, the Czechs failed to threaten in the latter stages, and Paulo Bento's side will face either Spain or France in the next round.