* Valencia into semis with 5-0 extra-time win over Basle
* Alcacer grabs hat-trick as Swiss side finish with nine men
* Sevilla thrash Porto to join compatriots in last four
* Competition favourites Juve beat Lyon 3-1 on aggregate
* Rodrigo double sees Benfica cruise past Alkmaar (Adds details)
By Toby Davis
LONDON, April 10 (Reuters) - Valencia turned the tables on a stunned Basle side to reach the Europa League semi-finals on Thursday with a 5-0 win after extra time thanks to a Paco Alcacer hat-trick as they recovered from a three-goal first-leg deficit.
It completed a good night for Spain as 10-man Sevilla tormented a fragile Porto side to win 4-1 on the night and secure a 4-2 aggregate victory while competition favourites Juventus and Benfica safely negotiated their quarter-finals.
Serie A leaders Juve beat Olympique Lyon 2-1 in Turin to go through 3-1 on aggregate with an Andrea Pirlo freekick and a Samuel Umtiti own goal while Benfica's Rodrigo scored twice in a 2-0 home win over AZ Alkmaar to complete a 3-0 overall success.
Basle, who were reduced to nine men in extra-time, went into the second leg 3-0 up and full of confidence at a highly-charged Mestalla stadium, but they came up against a Valencia side with the bit between their teeth.
No team had overhauled a three-goal deficit in a knockout tie since the Europa League started in 2009 but the hosts signalled their intent when Alcacer beat keeper Yann Sommer after collecting Joao Pereira's pinpoint pass in the 38th minute.
The impossible became faintly probable four minutes later when Eduardo Vargas headed home from Fede Cartabia's corner and the deficit was then wiped out with 20 minutes remaining as Alcacer rifled the ball into the top corner to send the home fans into raptures and set up a thrilling finale.
Alcacer missed a superb chance to win the tie in normal time but was denied by the excellent Sommer when one-one-one and the extraordinary match went into extra time.
Basle's task was made even harder when Marcelo Diaz was then sent off for kicking out and Gaston Sauro was dismissed after picking up two yellow cards in two minutes.
The almost inevitable winner arrived with six minutes of extra time remaining when Alcacer steered the ball home from close range after Pablo Piatti's cross and Juan Bernat made the tie safe by lifting the ball over Sommer when through on goal.
"The fans were with us to the end and it's an honour to have this support in the good times and the bad," Valencia's hat-trick hero Alcacer said in an interview with Spanish television broadcaster Gol TV.
"I missed a chance late in the game and I was really down on myself but then thank God I had another in extra time and I was able to put it away."
Twice UEFA Cup winners Sevilla, trailing 1-0 against Porto from the first leg, began the return with the momentum of a runaway train as they attacked relentlessly and took the lead after four minutes.
Carlos Bacca took a tumble in the penalty area and Ivan Rakitic dispatched the spot kick coolly into the bottom corner before Vitolo powered into the box and slid a neat low finish across the keeper in the 26th.
Three minutes later Sevilla inflicted further damage through Bacca, who was given time to turn and fire low into the net from 15 metres to make it 3-0 on the night.
The visitors were handed a lifeline when Coke was dismissed, leaving Porto almost 40 minutes to find a route back into the match.
They never posed a serious threat, however, and Sevilla increased their lead with 11 minutes to play when Kevin Gameiro added his name to the scoresheet.
The goal of the game, however, was scored by Ricardo Quaresma whose thunderbolt drive flew into the top corner but it was merely a consolation.
Juventus fans were treated to the familiar sight of Pirlo curling home a trademark freekick after four minutes that increased their aggregate lead to 2-0 and left the visitors needing to score twice to upset the odds and make the last four.
It was the sixth goal Pirlo had scored in all competitions this season and every one came from a direct freekick.
Lyon, the first French side to get to this stage of the Europa League, gave themselves a faint glimmer of hope when Jimmy Briand headed past Gianluigi Buffon after 18 minutes.
However, that hope was extinguished midway through the second half when Claudio Marchisio's long-range effort took a heavy deflection off Samuel Umtiti and beat Lyon keeper Anthony Lopes to restore the two-goal aggregate lead.
Last season's finalists Benfica effectively killed off Dutch opponents AZ when Rodrigo tapped in at the far post after 39 minutes following brilliant work by Salvio, who skipped out of one tackle and accelerated down the right before curling an inch-perfect cross into the penalty area.
The victory was wrapped up when Salvio put in another sumptuous cross from the right for Rodrigo to score his second.
The draw for the semi-finals is on Friday. (Reporting by Toby Davis; editing by Ken Ferris)