Kostas Lianos
Greek journalist to BBC Radio 5 Live

Image source, PA Media

Olympiakos do not feel like favourites tonight. They have dealt with all sorts of heartbreaks throughout their history, and they see this as a great chance to exorcise those demons of the past and make the next big step as a European club.

We've seen it before when Olympiakos have faced Premier League teams who were in a tough spot. With Manchester United in 2014 when van Persie hit a hat trick, with Liverpool in 2004 when Liverpool scored three second half goals including that famous one from Steven Gerrard, with Arsenal in 2016 when Olivier Giroud got a hat-trick. Tonight is the next big step for them if they can beat Villa.

Rachel Corsie
Scotland and Aston Villa captain on BBC Radio 5 Live

Image source, Getty Images

For the most part of the game tonight I think Villa will likely go with a three at the back. Ezri Konsa will have a role that involves more stepping out, he looks the most comfortable stepping forward and helping launch attacks.

Looking at the back three, four or five, however it may look, Pau Torres returning in place of Clement Lenglet is also key. He looks more comfortable in that back line, has played more minutes and can also step in and help to build out from the back too.

Dennis Mortimer
Aston Villa’s European Cup winning captain on BBC Radio 5 Live

In a game like this you don't just want one early goal, you want a couple. Villa are two goals behind and if they can get them quickly then the Olympiakos players will start to sweat a bit. The pressure will switch to them then.

Both teams let in uncharacteristic goals in the first game, particularly Villa. So tonight they have got to make sure that defensively they are on top of their game and the longer the game goes if they nick one back the pressure will be on the home side.

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Bayer Leverkusen boss Xabi Alonso says they want to use the agony of last year to spur them on this time.

These sides met at this exact stage of the same competition last season, with Roma the first leg 1-0 and drawing 0-0 in Germany.

This time though Leverkusen come into the second leg with a 2-0 lead thanks to goals from Florian Wirtz and Robert Andrich last week.

Alonso, who was also in charge last season, said: "It's a top game, with a top atmosphere. It's the semi-final of the Europa League - it's a big occasion.

"I still remember how we were welcomed by the fans on Bismarckstrasse last year [before the game] - it was unbelievable.

"We have not forgotten the pain of last year. We have to make use of this so we can celebrate with our fans at full-time.”

Former Scotland winger Pat Nevin expects Aston Villa will go all out to turn their Europa Conference League semi-final tie around in Greece.

Olympiakos won last week's first leg 4-2 at Villa Park, meaning Unai Emery's team must score at least twice to stand any chance of progressing to their first European final for 42 years.

Nevin told BBC Radio 5 Live's Football Daily podcast: "They [Olympiakos] know they've got a two-goal lead from the away leg - you can only shoot yourselves in the foot. If Villa score an early goal, absolutely all of the pressure is on the home side.

"There's no suggestion they're going to hold off in any way or will be keeping some players back for the league. They're going for this hammer and tongs."

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Ian Taylor
Former Aston Villa midfielder speaking on BBC Radio 5 Live

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When Emi Martinez is in goal he makes one hell of a difference to the team, we have that security of knowing we have a world class goalkeeper.

Robin Olsen has done well, he is a very capable number two but Emi Martinez is just a different class altogether.

Bayer Leverkusen

Bayer Leverkusen manager Xabi Alonso speaking to TNT Sports: "We have made a few changes. A few players who were not able to play from the beginning. We are facing a good team and let's see. It is a big chance that we have. We can't take anything for granted."

On his team selection: "Anyone can play striker. We want to fill the gaps and play between the lines, We need to have a good balance between passion and intelligence.

"We have a good advantage but it doesn't mean anything if we don't show a good performance today."

On the prospect of reaching the Europa League final and getting to 49 games unbeaten this season: "We all want more. The crowd will push us to go to Dublin. So far it has been great but we don't want to stop. The record is a consequence of the work we are doing."

Image source, Getty Images

Neil Lennon
Former Celtic manager on BBC Radio 5 Live

Villa have to forget what has gone on in the last couple of games where they have looked a little bit jaded, particularly in the second half against Chelsea, and then the defeat in the first leg last week and also against Brighton. This is it. It is all or nothing tonight. They have to dig deep and find those reserves of energy.

Fatigue means nothing at this stage of the season. If you think you are going to be fatigued then you will be fatigued. They have more or less guaranteed fourth place which is an unbelievable achievement, it would be incredible if they could make it a double success by making the final tonight.

Ian Dennis
BBC Radio 5 Live senior football reporter

When Unai Emery was at Sevilla in 2014 they had lost the first leg 2-0 and they turned around the two-goal deficit in the return leg and ultimately went through on a penalty shootout.

What [Olympiakos midfielder] Vicente Iborra was saying about Unai Emery was that he has taught him many, many things but the one thing that he did teach him during his time with European successes is that to get to the final you have got to want it more.

You have got to strive the most and have that positive outlook.

Aston Villa midfielder Douglas Luiz says he is "mentally strong" to take a penalty if required.

The Brazilian missed an 84th-minute spot-kick against Olympiakos in their 4-2 defeat in the first leg at Villa Park and is keen to make amends in the rematch at the Karaiskakis Stadium.

"I am the main taker and I know it is my responsibility," he said. "The one who takes is the only one who can miss. If we have another penalty, I will take it. I am mentally strong for that."

Villa have only picked up one point from their past two Premier League games and face a daunting task to overturn their two-goal deficit.

However, Luiz, who has played a central role in an outstanding season for Unai Emery’s side, was resolute in his faith they could triumph in Piraeus.

"We are confident and believe we can win this game," said Luiz. "This is a huge game for Aston Villa as a club.

"This season has been great for us and we have played really good football. I am really grateful for everything Villa has done for me and I want to try my best to bring them to the final."

There's going to be no shortage of atmosphere around the grounds in the Europa League and the Europa Conference League tonight.

Image source, Reuters

Image source, Getty Images

Image source, Reuters

Dennis Mortimer
Aston Villa’s European Cup winning captain on BBC Radio 5 Live

It has been a long time coming for these Aston Villa fans to be able to raise their voices and have a team that they can really cheer on. This has been that season for Villa. I can't see them not getting into the Champions League now, the position is more or less sound.

The thing they have to concentrate on more than anything else is this semi-final. Having watched the first game I thought it could have gone either way, I don't think Villa are out of it.

Even if Olympiakos score a couple of goals they have the capacity to beat this team. When Villa play well, they play well.

Image source, Getty Images

Jean-Louis Gasset is having an interesting season.

The 70-year-old was sacked by the Ivory Coast in January after the Africa Cup of Nations group stages - and they went on to win the tournament without him.

But weeks later he was named Marseille boss after they sacked Gennaro Gattuso.

They fell behind in the first leg of this tie to Gianluca Scamacca's goal but Chancel Mbemba levelled for the French side.

Gasset said: "In this squad, there are a lot of players who have played in big matches - internationals who know what this match means.

"We know what we have to do, we are ready to go to the end of the night to make everyone happy.

"I have never played a semi-final of anything, so at my age, I think you can dream."

Image source, Getty Images

Roma boss Daniele de Rossi says his side have to be "perfect" to knock Bayer Leverkusen out of the Europa League.

The Italian side are bidding for a third consecutive European final - with their Europa Conference League win and Europa League loss to Sevilla both coming under Jose Mourinho.

De Rossi, who replaced Mourinho in January, said: "We will have to continue looking for goals. We believe we can do it.

"We know it will be difficult, but we came here to win. What am I going to tell the team? I don’t know.

"Every now and then I prepare something. Sometimes I go off the cuff. I trust my boys. I have great faith that we will put in a good performance to try to achieve a minor miracle.

"We have no margin for error. Fortunately we can still turn things around but we need to be perfect."

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Ian Dennis
BBC Radio 5 Live senior football reporter

This place will be bouncing.

It holds about 33,000 but there will be only 1,600 Villa fans. It will be an intimidating atmosphere, that's for sure.

They are renowned, Olympiakos, for having strong European form.

Ian Taylor
Former Aston Villa midfielder speaking on BBC Radio 5 Live

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The first leg didn’t go quite the way Villa wanted it to but listen we are where we are. A lot of Villa fans have come here [to Greece] thinking, ‘We’ve got nothing to lose.’ They are all excited at playing in Europe and it is just exciting.

If we lose, we lose, but we are so much different than we were 18 months ago, when we were languishing at the bottom of the table and could only wish about being in Europe. Now we are just enjoying the ride.

We go away to Olympiakos tonight with no fear. I know it is going to be an intimidating atmosphere but being in the city as I have been for the last few days, there is a fear factor among the home fans with Villa coming here. We should take that into the game, take the match to them, we’ve got nothing to lose.

Aston Villa captain John McGinn, speaking after the 4-2 home loss to Olympiakos, said: "Not the game we wanted. We wanted a lot more control. We started the game well. They're a good side. We wanted a victory going to Greece. We showed we're capable of coming back.

"Mistakes all round. We'll take responsibility but it's up to us to go to Athens and turn it around because we're capable. They played very well tactically. They played the way we expected so there were no surprises.

"Everything that could have gone wrong did. The manager was still positive in there. There's still a long way to go. We need to play a lot better than we did but we're more than capable of doing it.

"The onus is on us to attack Olympiakos and score some goals. We have a mountain to climb but we know we're capable."

Image source, Getty Images

A week from now Atalanta could be in their first ever European final, have won the second trophy in their history and be in a Champions League place.

Or none of those things.

The Italian side, who are enjoying the best spell in their history since appointing Gian Piero Gasperini in 2016, have only won one major trophy before - the 1963 Coppa Italia.

On Sunday they face Roma, their rivals for the final Champions League spot in Italy, and on Wednesday they play Juventus in the Italian Cup final.

"In terms of the value of the goal, this match is the most important in Atalanta's history," said Gasperini.

"We want to reach the final, but we know we will need a great deal of concentration to do so.

"The most important factor will be the collective. The atmosphere in Marseille was extraordinary, but now that factor will be in our favour. The support from ours fans has always been great, even if we have a smaller stadium."