Colombian forward Radamel Falcao struck four second-half goals to help Porto battle back from a half-time deficit against Villarreal and leave the Portuguese giants all but through to the Europa League final following a 5-1 win at Estadio do Dragao.
Porto enjoyed plenty of ball on home turf, but Villarreal's counter-attacking game always threatened to create the opening goal. Nilmar should have opened the scoring inside 20 minutes when he ran clear, but he opted for the near corner when the far post was gaping beyond keeper Helton. The breakthrough eventually arrived on the stroke of half-time, with Cani silencing the home support from Nilmar's near-post cross.
Porto got an ideal start to the second half though, earning a penalty inside four minutes of the restart through goal machine Falcao, who was felled by keeper Diego Lopez. The prolific forward dusted himself down to send Lopez the wrong way from 12 yards, handing Porto a barely deserved equaliser.
The goal changed the flow of the game and they took the lead just after the hour, with Freddy Guarin nodding home after his initial effort had been parried by Lopez.
Falcao then added two poachers' finishes to complete his hat-trick, before a stunning header made it four for Falcao, five for Porto, and big trouble for Villarreal.
Meanwhile, Braga will take an away goal into the second leg of their Europa League semi-final, but it is Benfica who lead 2-1 after a gripping game at the Estadio da Luz.
Having conquered Liverpool earlier in their European campaign, Braga are the minnows of the competition's last four in comparison to fellow Portuguese giants Benfica and Porto. They were forced to spend lengthy spells on the back foot during Thursday's first leg, but a Vandinho header ensures they only have to score once next week to reach the final.
Benfica thought they had the lead inside 12 minutes as Oscar Cardozo slammed into the roof of the net, but his strike was rightly chalked out for offside. The big striker did have a telling say when the breakthrough did arrive however, heading against a post before Jardel stabbed the rebound home.
The lead lasted just three minutes as Braga hit back through Vandinho, who brilliantly diverted a goalbound free-kick into the corner of Roberto's net. However, Cardozo capped a superb individual display with the winning goal, slamming a free-kick into the top corner to hand Benfica the advantage.