UPDATE: A late change to the starting XI as Granit Xhaka picked up a knock in the warm up. Kieran Tierney comes into the side at left-back.
Villarreal XI: Rulli, Pedraza, Pau Torres, Raul Albiol, Gaspar, Parejo, Coquellin, Trigueros, Gerrard Moreno, Chukwueze, Alcacer.
Subs: Asenjo, Funes Mori, Bacca, Raba, Estupinan, Moreno, Pena, Jaume Costa, Moi Gomez, Pino, Alex Baena, Nino.
Arsenal XI: Leno, Bellerin, Holding, Mari, Xhaka, Partey, Smith Rowe, Odegaard, Pepe, Aubameyang, Saka.
Subs: Ryan, Okonkwo, Tierney, Gabriel, Lacazette, Willian, Cedric, Chambers, Nelson, Elneny, Nketiah, Martinelli.
Arsenal trail 2-1 from last week's first leg in Spain, but they have a number of key players returning to their starting eleven, including captain Pierre-Emerick Aubameyang. Which one of these two sides will be joining Manchester United in the final?
Hello and welcome to our coverage of tonight's Europa League semi-final second leg between Arsenal and Villarreal, live from the Emirates Stadium
KICK OFF: We're underway in North London!
Early corner for Arsenal as Tierney drives down the left before Pepe wins the set piece. Odegaard delivers, but Villarreal clear.
Save! Superb save from Leno as Villarreal threaten to score another early goal. Chukwueze curls an effort goalwards from the top right corner, but Leno makes a superb, leaping save to see the ball away for a corner.
Superb run from Chukwueze! Arsenal camp themselves round the Villarreal area, but Parejo cuts out a square ball from Pepe before sending his team-mate away. Pepe tries to stop him down that right wing, but Chukwueze skips past him. Mari then does well to initially dispossess him before Villarreal are again pushed back.
Good block from Tierney as Chukwueze causes issues again. He's picked out over on the right after a driving run through midfield from Pedraza, but the Arsenal left-back stands up well against the Villarreal winger.
A poor ball in midfield from Trigueros sees Odegaard with it at his feet, but there's no speed or urgency to try and create something.
Second Arsenal corner now, but there's a bit of a delay as the referee has a word with the muddle of players in the six-yard box. Odegaard delivers, but Rulli is above the throng to punch away.
A great ball over the top from Partey, picking out Pepe on the left. Pedraza is there to nick the ball away and into the arms of Rulli, but that is the right idea from Arsenal.
Over! Partey fouls outside the area. Free-kick for the visitors. Parejo goes direct, but it just lifts over Leno's crossbar. It lacked that last bit of dip - but it was very close.
Better from Arsenal! They drive forward with pace - finally - but Smith Rowe just cannot connect with a swinging cross from Saka. Tierney then tries his luck as Arsenal recycle the ball, but he sends his effort well wide.
POST! Corner for Arsenal. Odegaard's initial ball is cleared. Arsenal keep the ball alive, with Aubameyang's first cross back into the area seen away well by Parejo.
But the Arsenal captain gets another shot at it - literally - but he can only send his effort pinging off the bottom of the far post before going wide.
This is not what Villarreal will want to see - Chukwueze goes down of his own volition inside the Villarreal half, and he immediately signals that he needs to come off. Both sides use the opportunity for a quick team talk.
Substitution: Chukwueze is stretchered off. Worrying to see. Hopefully that's not too serious. 18-year-old Pino is on in his place.
Save! Pretty easy save from Leno as Gaspar tries to send in a cross from the right, but it goes straight at the goalkeeper.
Free kick in midfield for Arsenal as Coquelin is penalised for a pull back on Odegaard. Odegaard takes, trying to pick out Mari on the left, but the ball soon pings of the defender and behind for a Villarreal goal kick.
Close! Smith Rowe wins the ball in midfield before picking out Aubameyang on the left with a neat pass. The striker nicks pass Alibol before striking, but it looks like Rulli has it in his hands. But he spills his save and the ball bobbles away from him, but he manages to pounce on the loose ball before it wriggles over the line.
A few successive corners now for Villarreal, but Arsenal do enough both times to see the ball away.
Close! Another good break from Arsenal, who have been quicker on the counter-attack in recent minutes. However, Saka's final pass lifts well over the bar as Aubameyang lurks at the far post.
There will be three minutes of added time.
SECOND HALF: We're back underway! What a massive half for both sides. No changes at the break.
Close! Big early chance for Arsenal... It's a great flick through the two defenders from Tierney, into the path of Pepe. He steadies himself before striking - but it just fires past the far post. He wasn't far away at all.
HALF TIME: Villarreal are one half away from reaching the final. It was a pretty even half, Arsenal need to win the match to have any chance of reaching the final, so they'll be on the attack in the second period. It should be a good one.
Chance! So close for Arsenal. It's another swift attacking move from Arsenal, Bellerin sending in a cross from the right. Rulli comes out into the middle of the melee of players but does manage to flick the ball away like he intended. Smith Rowe it waiting just behind, stops the ball dead and has an open goal to aim for - but it just spins wide.
A break in play now as Gaspar and Pepe collide heads. Both look a bit winded, but are sitting up now.
Save! Moreno strikes - but it is straight at Leno! Partey is dispossessed in midfield, Alcacer is played through. He squares for Moreno, who finds his space to shoot, but it goes right at the goalkeeper.
Both Pepe and Gaspar are back on their feet and play is back under way.
Save! Another at the other end now as Pepe tries to square the ball for Aubameyang at the back post, but Rulli is there, down low, to make the stop.
Save! Great save from Leno as Pino flashes a cross into the six-yard box, but the goalkeeper is across to stick an arm out and see the ball behind for a corner. Comes to nothing.
Another injury stoppage. There are a few bodies down now - Odegaard in midfield with Alcacer and Mari also injured inside the area. Alcacer is soon back on his feet, but the two Arsenal men are still down.
Odegaard is back on his feet and limps way, but Mari is still in a bit of discomfort. Meanwhile, Martinelli is warming up for the Gunners and looks to be coming on imminently. Might well be for Odegaard.
Villarreal are keeping the ball pretty easily at the moment. Pedraza then sends a fizzing cross through the area, but Tierney is there to see it away.
Substitution: Martinelli is on for Odegaard.
Just over 20 minutes left for Arsenal to rescue their campaign.
Arsenal began this half well, but it has been all Villarreal in the last 15 minutes or so. They've been keeping the ball with ease with little in attack for Arsenal.
Arsenal win a free-kick in a promising position. Saka scoops the free kick in, Holding has the free header but it lifts over the bar.
Wide! Holding again. What a great delivery into the area from Pepe, but Holding just glances his header wide.
Wide! Saka delivers the latest Arsenal corner, Trigueros sees it away but Martinelli lashes his effort wide.
OFF THE POST! Aubameyang again! Aubameyang is picked out in the middle by Bellerin's superb cross, but his header hits the inside of the post before going wide. Again, the goalkeeper is beaten... Another big chance goes missing. That was Auba's last touch of the game...
Substitution: Double change for Arsenal. Tierney and Aubameyang are off. Willian and Lacazette on in their place. Lacazette takes the captain's armband from Auba as well.
Corner for Arsenal after some miscommunication between Torres and Rulli. Willian fires in a cross, but the defender and goalkeeper cannot get themselves sorted as the ball curls behind off Torres' head. That really could have gone anywhere.
Booking: Pino is into the book as he signals that a card should be given to Mari after another foul on him.
Superb block from Coquelin! He keeps his team now in it and hands Arsenal the corner, but it is sent in too deep.
Substitution: Two more Villarreal changes now as Pedraza makes way for Alberto Moreno.
We're into the first of five added minutes. Eddie Nketiah is on for Arsenal... and he's just been booked for a foul on Coquelin.
FULL TIME! VILLARREAL ARE IN THE FINAL! They will face Manchester United in the Europa League final. Unai Emery gets his revenge against his former club. For the first time in 26 years, Arsenal will not be playing in European competition next season.