Joao Pereira has warned Portugal must be at the peak of their defensive powers to negate the threat of Spain, regardless of whether or not they play with Fernando Torres.

The Iberian neighbours meet in the first semi-final of Euro 2012 in Donetsk on Wednesday evening, and the winner will face either Italy or Germany in the final of the competition.

Although Spain have yet to fire on all cylinders in this year's championships they remain undoubtedly the finest team on the planet, and Pereira is aware Portugal will face the sternest of examinations in the last four.

"We have a team with personality and we can't make any mistakes in the defence, because they (Spain) are very strong," the Portugal defender told a press conference.

"The players in the midfield are very strong and the passes normally are deadly, so we will try not to make any mistakes and exploit our attack."

In the absence of preferred striker David Villa, Spain coach Vicente Del Bosque has not settled on a favoured front line, opting to either pack the midfield with Cesc Fabregas at the tip or play Fernando Torres as a lone forward.

Both formations have proved effective for the reigning world and European champions so far, and Pereira expects Spain to provide equal threat with or without a striker.

"It's not important for us if Spain play with the same players, with Torres or without Torres," he added. "It's not important if they play with a striker or with six midfielders, it's the same."

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