Ruben “Cani” Garcia flicked a cross from Nilmar to put Villarreal ahead in the 45th minute after an evenly matched first half, but Porto completely dominated after halftime as Falcao took his competition-leading scoring tally to 15 with Freddy Guarin adding another for the Portuguese champions.
Porto will look to protect its comfortable margin in Spain next Thursday to set up an all-Portuguese final against Benfica or Braga, who ended their match 2-1 with Benfica sealing a vital advantage for next week.
Porto pressed up the pitch from the opening whistle with Cristian Rodriguez immediately lobbing a dangerous cross that goalkeeper Diego Lopez struggled to swat clear of the path of the oncoming Falcao.
Villarreal did not pass midfield until the seventh minute when Cani played Nilmar through with a perfectly weighted pass, but Porto goalkeeper Helton held firm to block the Brazil striker’s attempt.
Giuseppe Rossi broke through Porto’s vulnerable right flank in the 28th, rounding Helton, only for defender Ronaldo Ronesca to clear his goal-bound shot with a diving save.
Hulk had Porto’s best first-half chance four minutes later when his left-footed blast from outside the area grazed the post.
Villarreal’s opener was the payoff of a great team buildup started by Cani in his own half, and Lopez made a reflex save to deny Hulk’s low strike on halftime.
Falcao then put on an offensive display in the remaining 45 minutes, scoring from the penalty spot, with his left foot, and twice with his head.
Falcao blasted in a penalty kick after Lopez pulled him down in the area in the 49th to level the score.
Guarin then exposed the visitors’ defense with a strike that hit the post before he headed the rebound into the net in the 61st.
Behind in the score, Villarreal fell apart as Hulk raced free down the right side to assist the unmarked Falcao in the 67th.
Falcao’s fourth came when he headed in a free kick from Guarin, and he notched his fifth when he rose up to guide a header over Lopez in the 90th.
With its 13th straight victory overall, Porto boosts its chances of winning the triple crown after it claimed its 25th league crown with five rounds to play and faces Guimaraes in the Portuguese Cup final.
The first all-Portuguese semifinal in a continental competition burst into life in the second half with three goals in 10 minutes.
Center back Jardel poked the ball in from short range in the 50th minute after Cardozo’s header bounced back off the post.
Vandinho headed in the equalizer from a free kick three minutes later, then Cardozo — who had already hit the woodwork twice — found the target with a curling free kick.
Benfica hasn’t lost a game in the Europa League this season, and has lost only once in 59 games at home to Braga.
The return leg in Braga is next week.
“It was a good result for us but we deserved to win by a bigger margin,” Benfica coach Jorge Jesus said. “They never really caused us problems.” Benfica, which trails already crowned champion Porto by 19 points in the Portuguese league, lifted its last continental trophy 49 years ago when it was back-to-back European champion.
“It was an important win, but we have to press our advantage” in the return leg, Cardozo said.
Braga is third in the Portuguese league, 14 points behind Benfica. It has never come this far in a European competition and previously eliminated Liverpool, Seville and Celtic, but against Benfica it was far off the form that beat those clubs.
Benfica made most of the running at its Stadium of Light, with midfield playmaker Pablo Aimar leading the charge, but its attacks repeatedly broke down in the final third of the pitch.
Braga was nervous and its counterattack strategy was quickly contained by the home defense.
Javier Saviola provided Braga goalkeeper Artur Moraes with his first real test, volleying from the edge of the area in the 21st.
Cardozo broke through the Braga defense and shot against the post late in the first half, but it was little to show for Benfica’s midfield dominance.
Alain’s weak curling shot in the 42nd, scooped up without difficulty by Roberto, was Braga’s only first-half effort.
The visitors seemed happy to settle for the slim margin of defeat and defended with 11 men, leaving the decisive encounter for the second leg.
