(CNN) -- Radamel Falcao fired four goals as Porto demolished Villarreal 5-1 on Thursday night to all-but ensure an all-Portuguese final in the Europa League. 

The Spanish club took the lead through Ruben Cani just before halftime after dominating the opening period, but had no answer in the second spell against the Portuguese champions. 

Colombia striker Falcao extended his competition-leading tally to 15 this season, matching German legend Jurgen Klinsmann's record total in Europe's second-tier competition, while Fredy Guarin scored the other goal. 

Porto, who won the tournament in 2003 when it was still known as the UEFA Cup, will face either Benfica or Braga in next month's final in Dublin if they successfully negotiate the trip to El Madrigal. 

Benfica clinched a 2-1 victory at home, leaving the second semifinal evenly poised ahead of next week's return leg in Braga. 

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Villarreal, fourth in Spain's La Liga, had looked surprisingly comfortable away from home against a team that wrapped up the national league crown with five games to play -- and whose coach has everyone comparing him to his mentor Jose Mourinho. 

Andre Villas Boas could only look on as Ruben Cani headed Villarreal in front with a near-post effort from Nilmar's cross as Porto's defense was caught out again. 

But whatever the 33-year-old said at halftime, it did the trick as his team ran riot. 

Falcao equalized from the penalty spot three minutes after the break after being brought down by Diego Lopez, then just after an hour Fredy Guarin headed in a rebound after his first effort was pushed onto the post by the goalkeeper. 
Who scored Porto's other goal?
Fredy Guarin