Updated

By Simon Evans

PRETORIA (Reuters) - Spain coach Vicente Del Bosque is facing calls to replace striker Fernando Torres with Fernando Llorente for Saturday's quarter-final with Paraguay (2:30 p.m. EDT).

Media polls of fans in Spain have shown backing for a switch in attack but Del Bosque is still backing Torres to come good.

"It's impossible to avoid such a debate at a tournament like this because everyone has an opinion and it's good that they are expressed," said Del Bosque.

"Our forward at the moment is Fernando (Torres). He has played a part in all four matches, quite a few minutes, and he'll play more.

"We have full confidence in him and we also know that Fernando Llorente can bring a lot to the team," he added.

Llorente certainly has shown more verve than Torres, who came into the tournament not long after knee surgery, and brought extra life to the attack after replacing him in the 1-0 second-round win over Portugal.

European champions Spain must be at their sharpest against a Paraguay team who have conceded just one goal in four games and are searching for their first World Cup semi-final place.

The South Americans' last two outings ended 0-0 with a stalemate against New Zealand followed by an eventual victory over Japan after a penalty shootout.

In both those games Paraguay were experts in nullifying the threat from the opposition and the bad news for fans hoping for a wide-open game is that they plan to do just the same again.

"You are going to have a clash of two different kinds of football," said Paraguay goalkeeper Justo Villar.

"Their way is about creating and ours is more about stopping them and then taking our chances."

While forward David Villa, cutting in from the left, has been the main goal threat from Spain, the key to stopping their fluid passing game has often been to nullify playmaker Xavi and limit the attacking effectiveness of their two fullbacks.

Joan Capdevila down the left and Sergio Ramos on the right, provide the width missing from Spain's two-tier midfield but Paraguay have been adept at getting their forwards to defend.

Roque Santa Cruz showed against Japan that despite being a center-forward, he can drop off and effectively mark the opposition fullback.

If Paraguay can do that effectively then the game could well become a tightly congested encounter in midfield with few chances -- just the sort of game where the quality of finishing from strikers like Torres becomes all the more important.

(Editing by Ken Ferris)