European champions Spain admit they will have to lift a gear for their World Cup semi-final against Germany after progressing with a 1-0 win over Paraguay.

David Villa scored the only goal of Saturday's quarter-final at Ellis Park, his fifth of the tournament to keep him atop the golden boot standings.

The striker's winner came seven minutes from the end of what had been a disjointed quarter-final performance from the fancied Spaniards in a game that saw both goalkeepers save second-half penalties.

Germany, who lost to Spain in the Euro 2008 final, had earlier thumped Argentina 4-0 in Cape Town.

"We didn't play well mainly because we didn't get enough of the ball," said Spain coach Vicente Del Bosque.

"We are now amongst the four best teams in the world. Our next opponents are Germany who are the best team at the moment."

Spain's Cesc Fabregas, who came on for the out-of-form Fernando Torres in the second half, admitted the semi-final will require a step-up in class.

"It feels good to be in the semi-finals but we know it'll mean nothing if we don't reach the final," he said.

"We watched Germany beat Argentina and they played very well. They are one of the best teams in this tournament. We will have to play our very best to be able to beat them."

Paraguay coach Gerardo Martino said his side paid the price for not taking the opportunities which came their way.

"We had chances but didn't take them. But never mind. I congratulate my players for their progress at the World Cup," he said.

Paraguay made a good start to the match and created two chances in the first 10 minutes.

Jonathan Santana shot too close to goalkeeper Iker Casillas from 20 yards and then Cristian Riveros failed to hit the target with a header from Victor Caceres' pinpoint cross.

Spain were out of sorts with even Barcelona playmaker Xavi uncharacteristically wasteful with his passing.

However, he finally brought a spark to the European champions' play when he hit a dipping volley from 23 metres just over the bar.

Four minutes from the break Paraguay had the ball in the net as Nelson Valdez latched onto a long ball and slotted home into the bottom corner but his strike was ruled out for offside.

Liverpool forward Torres remained an isolated figure up front and it was not surprising that Spain coach Vicente del Bosque replaced him with Fabregas.

The game burst into life around the hour mark.

Paraguay had a golden opportunity to take the lead on 59 minutes when Gerard Pique was penalised for hauling down Oscar Cardozo in the box.

But Cardozo missed the resulting penalty with Spain captain Casillas guessing the right way to make the save.

Spain then went straight up the other end and Antolin Alcaraz was adjudged to have tripped new Barcelona signing Villa in the area.

Xabi Alonso stepped up to bury the penalty but was ordered to retake it as Spanish players had encroached.

Second time around he changed sides but Justo Villar then guessed right and saved before Sergio Ramos' follow up was blocked on the line.

Brought to you by AAP © 2024 AAP