* Porto are on an incredible run of form this season. They are unbeaten in the league and have lost just twice in all competitions - to Sevilla and Benfica.
* The recently crowned Portuguese champions have won just one of eight European games at home to Spanish sides since the turn of the millennium.
* Porto have a mixed record from their two European semi-finals against Spanish teams, both in the Champions League. They were knocked out in 1994 by Barcelona but they eliminated Deportivo ten years later.
* Striker Radamel Falcao is the competition's leading scorer with eleven goals and he will line up against Giuseppe Rossi, just behind on ten.
* Villarreal have avoided defeat since going down 1-0 to Greek outfit PAOK in the group stage - a run of eight games.
* This is only the Yellow Submarine's second appearance in a European semi-final - they lost to Arsenal at the same stage in the Champions League back in 2006.
* Surprisingly for such an attacking team, Juan Carlos Garrido's side have yet to score in the opening 15 minutes of a Europa League game this season.
* Highly-rated goalkeeper Diego Lopez is one of just two players to have played all 1080 minutes of action since the competition entered the group stage - his Porto counterpart Helton is the other.
PROBABLE LINE-UPS
Porto (4-3-3) : Helton; Sapunaru, Rolando, Otamendi, Alvaro Pereira; Guarin, Fernando, Joao Moutinho; Cristian Rodriguez, Falcao, Hulk
Porto coach Andre Villas-Boas will line the team up in his favoured 4-3-3 formation. Cristian Sapunaru will assume the right-back position as Uruguayan full-back Jorge Fucile has been ruled out for the rest of the season with injury. The major selection quandary for Villas-Boas is whether to recall the fit-again Fredy Guarin to midfield or to stick with the in-form Ruben Micael. Cristian Rodriguez should get the nod upfront alongside Hulk and Falcao ahead of Silvestre Varela.
Villarreal (4-4-2) : Diego Lopez; Mario, Marchena, Musacchio, Catala; Santi Cazorla, Bruno, Matilla, Borja Valero; Rossi, Nilmar
After missing the second leg quarter-final in Enschede with suspension, Nilmar is back in this competition to take his place alongside Giuseppe Rossi in one of Europe's best strike partnerships. Experienced campaigner Carlos Marchena has shifted back into defence after a spell in midfield to add some solidity to an otherwise inexperienced back four, which is shorn of Angel and Gonzalo Rodriguez. Marcos Senna will travel to Portugal but is very unlikely to appear. Borja Valero will return to the starting eleven in place of young winger Wakaso
Mubarak.
Prediction
Porto 2-1 Villarreal 
