Porto completed their demolition of Spartak Moscow by following up last week's 5-1 in Lisbon with a 5-2 victory in Moscow in their quarter-final second leg to complete a 10-3 aggregate win.
Benfica went through with an impressive fightback at PSV Eindhoven where they went 2-0 down in 25 minutes but hit back to draw 2-2 and reach their first European semi-final for 17 years 6-3 on aggregate.
In complete contrast, Braga, Liverpool's conquerers in the last 16, went through with a goalless draw at home to Dynamo Kiev, qualifying on away goals after their 1-1 draw in Ukraine.
Braga held on despite having Paulo Cesar sent off before the half hour.
Spain's Villarreal will be the odd ones out after coming from behind to win 3-1 away to Twente Enschede for an emphatic 8-2 aggregate win.
A final between former European champions Porto and Benfica is on the cards with Porto facing Villarreal in their semi-final and Benfica meeting Braga.
Porto, who fielded nine South Americans in their starting line-up, maintained their 100 percent record away record in the competition with seven wins out of seven.
Striker Radamel Falcao took his Europa League tally to 11 goals this season as he was among the scorers on a chilly Moscow evening for the recently-crowned Portuguese champions.
"We wanted to score an away goal and fortunately, we managed this, maybe in the moment in which Spartak were creating some chances," said Porto coach Andre Villas-Boas.
"But we need to give a little more than we did today - more commitment, demand more of ourselves - to reach the final, which we really desire."
HULK SCORES
Brazilian striker Hulk and Uruguayan midfielder Cristian Rodriguez gave Porto a 2-0 half-time lead before Colombian pair Fredy Guarin and Falcao added two more early in the second half.
Artem Dzyuba and Brazilian striker Ari replied for Spartak before Porto substitute Ruben Micael fired in the fifth in the 89th minute.
Porto, who have won 24 out of 26 league games this season and 12 out of 14 Europa League matches, will face Villarreal after the Spaniards scored three times in the last half hour against the Dutch champions.
Villarreal, leading 5-1 from the first leg, fell behind to a superbly-worked goal finished off by Swede Emir Bajrami in the 32nd minute.
Second-half penalties converted by Italian Giuseppe Rossi, his 10th goal of the competition, and Marco Ruben put the Yellow Submarine back in control before Cani added the coup de grace.
Benfica, 4-1 ahead after their first leg, had a bigger scare at PSV, where Jermain Lens set up the first goal for Balazs Dzsudzsak in the 18th minute and scored the second himself seven minutes later.
The Eagles were wobbling until captain and defender Luisao volleyed in an acrobatic goal with the last kick of the first half and Paraguay forward
