It was a night nobody involved in will ever be able to forget.

For Liverpool, the Champions League semi final second leg against Barcelona was the tipping point when three-and-a-half years of promise under Jurgen Klopp crystallised into glorious reality.

24 hours earlier, that progress had seemed suddenly perched on a precipice. Vincent Kompany's thunderbolt for Manchester City against Leicester had felt like the final hammer blow to the Reds' fading hopes in a never-before-seen slugfest of a Premier League title race, meaning a likely 97 point tally would almost certainly not be enough to end that 29-year wait for a 19th league championship.

And the previous week's scarcely-believable three goal defeat, despite outplaying Barcelona for long stages of the Camp Nou first leg, had surely meant a season of remarkable quality and consistency was now almost certain to end in more empty-handed heartbreak.

READ MORE: ‘Worst player in best team in the world’ - from sleeping in a shed to Liverpool icon and inventor of Adidas Predator

READ MORE: 'Rafa clearly did not read the Premier League rules' - Alex Ferguson's fury over Liverpool transfer bid

For the visitors from Catalonia, this was an opportunity to exorcise the ghosts of the previous season's surrender in Rome when they had lost a three-goal home first leg lead and crashed out in the quarter-finals.

Barcelona' whole season had been predicated on winning the Champions League back after rivals Real Madrid's three successive wins following their last triumph in 2015, captain Lionel Messi's speech to his players at the start of the season about how it must be their primary focus being widely reported and channelled through much of their campaign.

As we know, Liverpool produced the most astonishing comeback of even Anfield's exalted history and went on to lift the trophy with victory over Tottenham in Madrid, European Cup number six being the springboard for a remarkable Premier League campaign which ended in a first league title in 30 years.

Towards the end of 2019, Rakuten released an eight-part documentary about Barcelona's 2018/19 season called Matchday: Inside FC Barcelona, the penultimate episode of which focuses on that epic second leg at Anfield.

A trailer released at the time showed the horrified reactions of pop star Shakira - wife of Barcelona defender Gerard Pique - as the tide turned in the Reds' favour but closer examination of the episode reveals a fascinating insight into one of the greatest nights in Liverpool's history and the reverence Barca have - even in advance of the game - of the power of Anfield. Yet they are still powerless to do anything about it.

We've broken down the best bits below for you to enjoy...

PRE MATCH

The scene is the idyllic surroundings of the Abbey of Montserrat in Barcelona with two priests going about their daily business.

"Are you thinking to watch the match against Liverpool?", one asks the other.

"Well I think I'll make the effort", he replies, "because even though we have to get up at half 5 to go to matins I want to watch it.

"There are good prospects especially after the 3-0 at home, I hope we can hold on well.

"And what's more Barca is a symbol of our personality.. today loyalty is lost.

"Loyalty is lost in politics, they go from one party to another.. loyalty is lost in families.

"But the loyalty that is maintained? To Barca!".

Midfield lynchpin Sergio Busquets looks relaxed and confident in his car, speaking hands-free on the phone to a friend telling him to make the most of the experience ahead of him in Liverpool but warning of the 'factor of the stadium'.

"You always watch it on tv and the song they sing before and how close the fans are", Busquets says.

"And well, I'm excited to play there and experience that environment.

"I really want to play in Anfield because of the stadium it is. It is incredible that the crowd is so much with their team, they are always on top of all the play.

"From the first minute the game starts until it ends, they are with their team.

"As a player, these are the things you like to experience."

The second leg will be the first time Philippe Coutinho has returned to Anfield since his £142m transfer from Liverpool to Barcelona 16 months earlier.

"Really it is something that has stuck in my memory", he says, "the entrance onto the pitch and the fans singing "You'll Never Walk Alone".

"It's like it's a twelfth man on the pitch. Without doubt it's a tough match for us."

You can tell from the expression on the Brazilian's face these are not the normal platitudes footballers sometimes employ. Coutinho knows this to be true.

Next we're at the airport the day before the game as Barcelona set off for Liverpool and, after arriving at John Lennon airport, attention turns to the pre match press conference attended by coach Ernesto Valverde and Luis Suarez who is also returning to Liverpool to play in a competitive game for the first time since his own move from Anfield to the Nou Camp in 2014.

We see them travelling through the narrow streets surrounding Anfield and Suarez reminisces on the three and a half years he spent in the city, having already admitted his family insisted on returning to Liverpool with him as soon as the semi-final draw paired his current and former clubs.

"Where I lived, two blocks away was John Lennon's house, which is also a walk", he says. "The tourist bus always passes by.

"Next door was Skrtel, Maxi Rodriguez lived in the other, Pepe Reina in another and Fabio Aurelio was there.

"We would have barbecues and all coordinate to go to training at the same time, because if not, "Why did that one arrive an hour before, why the other?"

The Barca press staff talk about the news Salah and Firmino will be both be unavailable through injury for the second leg which Klopp has confirmed in his media briefing a couple of hours earlier, "From Klopp, there's not much else. He said they'll try to mount a comeback." But they don't look too worried.

The camera cuts to a barbers off Dale Street in Liverpool city centre where the talk is of the game ahead and whether Liverpool can somehow pull off another European miracle. "Confidence is key. No matter how good your players are, no matter how many leagues you've won you can't beat an atmosphere like Anfield's. Whether it's 90,000 or 70,000 or whatever, it feels more like a big family than just a club."

Meanwhile by the Albert Dock, we see Barcelona fans arriving, enjoying fish and chips and taking in the city's sights

"Let's go for the sixth" is the cry they greet each other with, the Blaugrauna - like Liverpool - currently having five European Cup wins on the board and hoping to move ahead of their hosts and fellow quintuple holders Bayern Munich into third in the all-time list behind AC Milan and Real Madrid should they prevail tonight and in the Madrid final.

The fans know they are going into the lion's den though, even with a three-goal first leg advantage.

"The people will pressurise them. The moment of the hymn.. It has to be awesome. The moment of the hymn gives you goosebumps."

Back at the Anfield press conference, Suarez says their collapse in Rome thirteen months before means Barcelona are even more alive to the threat of complacency and are determined there will be no repeat.

"We have thought long and hard about this, about what happened most recently last year. You have to be alert and learn from your mistakes, don't you?".

Lionel Messi appears on camera to expand: "It was very hard because we relaxed, we were overconfident and we thought we were already in the final and that match shows you what the Champions League is."

Coach Valverde is asked by Catalan radio if it is impossible for what happened in Rome to happen again against Liverpool at Anfield

"In the same way as we have won, we have to concede that our rival can beat us", he admits.

"But seeing this press room full and seeing what the stadium is going to be like tomorrow, I think there'll be little relaxation."

MATCH DAY

Now it's down to the real business and we see Anfield just over three hours ahead of kick off on match night.

Catalan radio provides the background with the stirring intro, "The day has come. The moment of truth has arrived.

"It's all or nothing. The ticket to the Champions League final is at stake.

"Anfield is going to be bouncing. "

Barca fan and 'YouTuber' Andrey Kirov records a video outside the Shankly gates and says, "Hey friends, I'm at Anfield stadium.

"'You'll never walk alone', finally I am going to hear it live for the first time.

"This is a very special moment of all or nothing. We either keep going or.. "

And then we're inside the ground as You'll Never Walk Alone begins for real.

As Gerry Marsden's dulcet tones ring out, we see Kirov filming the spectacle on his phone with a look of sheer wonderment on his face before meeting for the first time three clearly time-served Barca fans watching on television, presumably back home at Catalonia.

While watching the pre-match spectacle, one says "They call them the red devils". This isn't the only thing they'll get wrong as the evening draws on.

Shakira from Columbia doesn't join in the singing with Gerry from Toxteth as we're taken inside the home she shares with Barca defender Gerard Pique and their two young children, who are playing with toys in their pyjamas as they wait for the match to begin.

Inside the Barca dressing room, all is quiet as the players stretch and make their final preparations. Quiet that is apart from the sound of the Liverpool 'hymn', which is clearly audible.

As YNWA reaches it's climax, it does grab the attention of Shakira and her brood who are now watching intently, while inside the dressing room we hear the final words of encouragement before the Barcelona players take to the field.

"We are prepared to suffer, we will suffer, it's going to be tough." But they have no idea just how tough.

Messi leads the final blast: "Come on people! We are going to take a step forward.

"We can't waste this opportunity, ok? Give everything, now that we are here.

"We have to start strong, remember Roma was our fault. Our fault and nobody else's."

THE GAME

The match begins. We all know what happened but it's fascinating to see it through Barcelona eyes.

Andy Robertson's early run in with Lionel Messi has the match commentator remarking on the 'problem' Liverpool's Scottish full back had with Luis Suarez in the first leg and he suggests Messi needs to 'calm down'..

"My word, so much excitement today in Anfield. This is the toughest atmosphere I've seen in years."

His co-commentator remarks, "I've never seen anything like this in my life."

Jordan Henderson of Liverpool celebrates as Divock Origi (R) scores

Divock Origi gives Liverpool a seventh minute lead and, with trepidation, the commentator says "And Klopp asks the Liverpool fans to cheer even louder!"

Back in Barcelona, the three fans watching on tv groan and say, "This is not going well but there is still a two goal margin. There's a lot of time left and no need to panic."

As Barcelona begin to threaten and create chances of their own, Coutinho is denied by Alisson and Messi shoots narrowly wide leading to grimaces from Shakira.

Her son asks, "If it finishes 3-1, do we still go to the final?"

"Yes", she says,"close again", but the anxiety her husband and his team are facing is etched all over her face.

At half time in the Barca dressing room, the tension is writ large.

Speaking after the event, Gerard Pique says "When they score the first goal very quickly then I suppose the ghosts of Rome appear."

Goalkeeper Marc Ter Stegen adds: "We hoped Liverpool's energy would drop somehow and we'd be able to find our own way but it wasn't easy.

We hear coach Valverde's half time instructions to his players: "We have a problem because they are pressing us and also they are all in the centre.

"We need to push up. When we take the ball off them, it's brilliant. Once we've got the ball, we move a bit inside, we hook up with Leo, go forwards and we can come in from the other side without any problems.

"But the question is being there strong. Every time we get the ball from them, we're dangerous. Everything will be decided here, near their area."

As they prepare to leave the dressing room, the Barcelona players encourage each other: "We can do it.. we have to be strong.. we have to score a goal.. we have to score a goal", with Luis Suarez exhorting his colleagues: "We cannot let them score again".

The Uruguayan knows what Anfield is capable of with its tail up and he is not wrong.

Because seven minutes after the interval, Gini Wijnaldum sweeps home Liverpool's second on the night from Trent Alexander-Arnold's deflected cross to reduce the deficit to one goal and the Catalans' worst fears are rapidly becoming reality.

Marc-Andre Ter Stegen of Barcelona fails to stop Gini Wijnaldum of Liverpool from scoring his team's second goal

Even as the attack builds, the match commentator says "Anfield is coming alive, Barca is suffering" and once the goal goes in, the alarm bells have become clanging chimes of doom for Barca and their supporters.

"Son of a mother" curses Shakira, while the commentators says perhaps more in hope than expectation, "Now we'll see Barca's character".

Liverpool go straight back on the attack and one of Shakira's sons tries to comfort her, saying: "If it stays like this, it doesn't matter. We'll go through to the final."

But it doesn't stay like that. 122 seconds after Wijnaldum's first goal, the Dutchman guides a pinpoint header from Xherdan Shaqiri's left wing cross into the same Kop end net to equalise on aggregate and Anfield explodes.

"No! I can't believe it!", Shakira screams.

YouTuber Andrey Kirov buries his face in his hands in the Anfield Road alongside many Barca fans doing the same.

"It's the eternal nightmare! Each and every one of the ghosts are reappearing", bemoans the Catalan commentator.

"What happened there?", Shakira asks her young son but he doesn't know. No-one does.

Full back Sergi Roberto speaking after the event explains, "They were attacking and attacking, now with their spirits through the roof, we had our spirits rock bottom.

"I didn't stop looking at the score, I couldn't believe what was happening."

Hopes rise of the away goal Barca are now desperate for as Messi wins a free kick on the edge of the Liverpool box after a foul by Joel Matip.

The three old-timers back in Barcelona cling on to the hope of salvation by their Argentinian superstar like drowning men to lifecrafts.

"Messi always scores, this is the one that will save us. Let's cross our fingers..", one of them says.

But it doesn't work, Matip and van Dijk jump high in the defensive wall to block Messi's shot and 50,000+ Liverpudlians in the ground as well as millions around the world breathe a sigh of relief.

Shakira and Pique's little lad is still trying to keep his mum's spirits up.

"It doesn't matter how, ok?", he says. "We need to score a goal, no matter how."

"Yes, my love, yes", she replies. The kid just blows his cheeks out, an expression of helpless fatalism any football fan young or old will know only too well.

And then it happens. Possibly the cleverest and cheekiest goal in Anfield history. As the clock ticks towards the final ten minutes of the 90, Trent Alexander-Arnold wins a corner down the Liverpool right.

With the Barcelona defence dazed and confused from the intense pressure they've been under, the young Scouser spots an alert Divock Origi looking his way and sends a quickly-taken but accurate low cross in the Belgian striker's direction while those in the bright yellow shirts - hardly any of whom are even looking in the direction of the ball - are still thinking about where they might stand for the corner.

The Belgian watches the ball carefully onto his instep and guides the ball into the top corner of the net to put Liverpool ahead in the tie for the first time.

Divock Origi celebrates after scoring the fourth goal during the UEFA Champions League Semi Final second leg match between Liverpool and Barcelona at Anfield on May 07, 2019

We see Luis Suarez looking pleadingly at a linesman hoping for a flag but he knows this is a piece of street-smarts he would have been proud of himself.

Back at chez Pique, Shakira sits mute and shell-shocked with her hand over her face. The kids have been packed off to bed now and the screen shows the man of the house thousands of miles away at Anfield wondering how this has happened to him again.

The three fans watching together in Barcelona cannot speak. One just looks to the heavens and sighs "Oh!"

The scene inside the Barcelona dressing room when the players return is one of abject devastation.

Not a word is spoken. The only sound is of that of the showers running and club staff going about their business, putting drinks out and tidying mess away. Many of the players cannot even bring themselves to get changed.

Thousand yard stares are everywhere, accompanied by the occasional disbelieving shake of the head.

Messi looks on the verge of tears. Suarez looks like he wants to batter someone.

THE AFTERMATH

The scene turns to a grey, miserable, rainy, thundery Barcelona training ground after the players have returned home.

A series of players including Pique and Ter Stegen as well as coach Valverde appear on camera but cannot speak. What can they say? Their worst nightmare has played out before them. Again.

Eventually Stegen speaks and says: "After a match like that, the first thing you want is to disappear.

"I felt terrible for the people, for the fans who travelled.

"We all the same goal to reach the Champions League final and simply I'd like to say thank you for the atmosphere and ask them for forgiveness for the result

Pique adds: "It was a bit of everything but most of all it was a mental issue. We'd had the recent game against Rome, and whether you like it or not, however much you try not to think about it, you try to flip it.. but everything was very similar to that experience and you end up with the same result. It is very hard."

Coach Valverde explains: "When you take a hit of this type, what you often do is take shelter in your family, in yourself and forget about everything.

"And you try to rationalise everything, within what is irrational that a defeat becomes.

"In the end, you always think if you could or should have changed something, or not changed anything. With the game against Rome, I thought about it many times and I prepared it knowing the experience of the previous year.

"I have the feeling that if I started again I think that I was wrong about something, I would be wrong again.

Sergi Roberto, hero of Barca's own miracle comeback from a four-goal first leg deficit against Paris St Germain two years earlier says they are hurting but no-one more than their captain and talisman, Messi.

"Leo was really screwed up after the Liverpool game", he says.

Lionel Messi of Barcelona looks dejected as the scoreboard reads '4-0'

"As captain, making that speech at the start of the season saying that we would bring the Champions League home to the fans, I think more than anyone, he was really hurting and very sad."

Barcelona had clinched the La Liga title the weekend before the first leg of the semi final against Liverpool and, while their Champions League exit clearly cast a shadow over their campaign, they still have a shot at some form of redemption with the final of the Copa del Rey against Valencia still ahead.

We see 'Captains' Messi and Pique meeting the press ahead of the clash in Seville and they make it very clear how desperate they are to put the Liverpool defeat behind them and end the campaign on a high.

"We are the only ones responsible for that match", says Messi, "because we knew that the same thing as last year couldn't happen, but it did.

"I think the match we played was pitiful, the image we gave.

"More than the fact there were failures, mistakes, errors, the worst thing is - and we can't forgive ourselves for this - is that we didn't compete.

"This is why we ask for forgiveness, not for having lost the match but for not competing for the pass to the final."

But the scars of Anfield are deep and Barcelona lose the final to Valencia 2-1, the final act of an '18 day storm' which left the Catalans desolate and Liverpool on the brink of the European glory.

*A version of this article was originally published in 2020.