The match was billed as a meeting between the second- and third-ranked teams in the world but the 1-0 scoreline gave little sign of the real gulf between the Iberian neighbours.
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"We always controlled the game but in the second half we were better than Portugal, we had greater depth in our game and we controlled very well," said Spain coach Vicente del Bosque.
"Given the number opportunities, Spain had their victory and it sits well with what happened in the game," said coach Carlos Queiroz.
"It must be recognised that Spain moved the ball extremely well and had a greater degree of possession.
"We had a number of opportunities but we allowed Spain to play the same type football up to the point where they scored."
Spain looked dangerous from the off as Fernando Torres and Villa stung goalkeeper Eduardo's palms three times cutting in from the left in the opening seven minutes.
Portugal plugged that gap however and, settling about their task, worked hard to ensure Spain's crisp passing made patterns in the midfield instead of inroads towards goal.
Spain continued to dominate possession after the break but struggled to find a way through until Del Bosque's inspired substitution after 58 minutes.
His presence upset Portugal's concentration and spurred Spain to accelerate their approach.
It paid off decisively in the 63rd minute when after another crisp move from deep, Xavi cleverly rolled Andres Iniesta's pass into the path of Villa and though the forward's left-foot shot was saved he reacted quickly to ram in the rebound with his right for his fourth goal of the tournament.
