Spain's hopes of becoming the first team to win back-to-back European championships are still intact after they overcame Portugal in a dramatic penalty shootout in the semi-finals of Euro 2012.

Following 120 minutes in which neither side could break the deadlock, Vicente del Bosque's side were left to hail the influence of the woodwork as Bruno Alves's venomous spot kick rebounded off the crossbar, while Cesc Fabregas slotted home the decisive strike off the inside of the post.

Portugal frustrated Spain during the opening 45 minutes as the reigning world and European champions were restricted to shots from distance, with Alvaro Arbeloa and Andres Iniesta both going close.

Cristiano Ronaldo and Nani were a constant threat and the former almost opened the scoring on the half-hour mark, but his low left-footed shot dragged narrowly wide from 18 yards.

Portugal began the brighter after the break and, after only nine minutes of play in the second half, Del Bosque decided that enough was enough.

The Spain boss, who had named Sevilla's Alvaro Negredo in his starting XI, hauled the disappointing forward off in favour of Fabregas and reverted to his infamous 4-6-0 formation.

The change seemed to have a positive effect as Spain began to hold on to possession much more effectively, however they continued to struggle to break down their opponent's backline and it was Portugal who went closest to finding a winner in normal time.

First Ronaldo had a reasonable shout for a penalty kick turned down as he tumbled under the challenge of Sergio Ramos.

The former Manchester United star then fired a trademark free kick a whisker over from 25 yards.

Then, in the final minute of the 90, Portugal broke rapidly following an unsuccessful Spanish set-piece. Raul Meireles put Ronaldo in the clear but he slashed high and wide from 10 yards out.

With their opponents' entire back four carrying yellow cards, Spain sensed blood at the beginning of extra time and began to dominate the contest for the first time in the evening.

Rui Patricio was forced to pull off an unbelievable save to deny Iniesta from point-blank range, before Fabregas went close from distance and Jesus Navas was stopped in the six-yard box by a last-ditch Pepe tackle.

Portugal hung on for dear life and managed to take their rampant opponents all the way to a shootout, where Fabregas eventually made himself a hero.