In a truly historic night, Liverpool thrashed Barcelona 4-0 at Anfield to qualify for the Champions League final. The Reds overturned a devastating 3-0 first-leg defeat to qualify for their second consecutive Champions League final. What did we learn?

1. Ladies and Gentlemen, Trent Alexander-ArnoldWhen you're 20 years old and playing in your second Champions League semi-final, chances are you've made some good decisions in life. When you then proceed to continue to make good decisions pretty much all night long then chances are you might be pretty special.

Alexander-Arnold was left out of the first leg for fears over his defensive weakness being exploited by Barcelona. In the second leg, 3-0 down, Klopp had no option but to trust his miraculous young full-back and just hope that the Blaugrana wouldn't get at him.

Well, they did get at him a bit in the first half, and Klopp may have been feeling nervous, but Coutinho's performance spiralled into oblivion and Luis Suárez ran out of gas, so in the second half Alexander-Arnold found new freedom to attack. And that's when it got real.
A superb bit of play to skip by Jordi Alba and one bullet of a low cross (deflected, to be fair) later, Alexander-Arnold had created a second goal. Suddenly a comeback seemed actually plausible. Anfield roared to life and when Wijnaldum made it 3-0 later a winner seemed inevitable. And of course, it was Alexander-Arnold who provided it.

A corner is always a good chance to score a goal, there can be no doubt about that. But usually it's because of a towering physical effort from a player in the middle.
This time Alexander-Arnold saw the Barcelona players slacking and simply scorched in another low cross, a beauty of a thing that took everyone but Gerard Piqué by surprise, and allowed Divock Origi to hammer a winner home. Anfield erupted, all because of the improvisational genius of a kid, the coolest kid in the stadium. Ladies and Gentlemen, Trent Alexander-Arnold.

2. Roma Revisited: Ernesto Valverde is a cowardBarcelona entering the second leg of a European tie with a three-goal lead and put out an XI with no pace. This invited their opponents to press relentlessly and as a result they were overwhelmed and capitulated in a most ridiculous manner. The most ridiculous manner.
Now which game does that describe, Roma in 2018 or Liverpool in 2019? Trick question, it's both. Ernesto Valverde somehow made the same mistake again. Inexplicably made the same mistake again. The same mistakes again, really.

The same defensive line-up focusing on playing Liverpool at their game (Arturo Vidal being frenetic) than Barcelona playing their own (Arthur being composed). It was absurd to see Sergi Roberto, defensively culpable for two of the four goals conceded, start the game at right-back ahead of the defensive powerhouse Nelson Semedo.
The same reliance on Luis Suárez to lead a counter-attack when the man couldn't lead a spinning session at the local gym if it went longer than 30 minutes.
The same utter failure to provide Lionel Messi with anything in the way of a consistent out-ball in attack for him to make use of NOR get him the ball in promising positions, forcing him to dribble through four players to get a decent look at things.

The same nonsense bringing on his only fast forward when the opponent has finally taken the lead and thus will no longer play high with space in behind where pace could have been deadly. That same every god d*mn thing. Well, the only difference between Liverpool and Rome is that Coutinho played this time and Barcelona were wearing volt instead of blue.
If Ernesto Valverde makes it to the end of the season it will only be because Barcelona feel he deserves to have the chance to win the Copa del Rey final against Valencia.
Based on his hysterical failure to learn from his lessons and his continued stifling of Barcelona with his cowardly tactics and bottle a three-goal lead in Europe for two years running, he deserves to be sacked. Instantly, if we're being honest. They should leave him in Liverpool.
3. Three-Minute WarningGeorginio Wijnaldum came off the bench at half-time because of a knock to Andrew Robertson and took up position in central midfield. Unlike the midfielders who started, Wijnaldum is a serious threat in attack because he has sensational timing and an incredible athletic ability to leap into the air despite not being the tallest guy.

Back when Liverpool came from 3-0 down in the 2005 Champions League final against Milan the goals all came in a magical six-minute spell. Well at Anfield they were more spread out but two of the goals, the two which turned this comeback from “never give up!” to “hey, it's on, this!” came in a furious three-minute spell where Wijnaldum showed those killer qualities of his.
First his supremely well-timed run, held back long enough that he arrived at the top of the box to perfectly meet Alexander-Arnold's shot with a rasping strike so low and hard that Marc-André ter Stegen couldn't keep it out even though he got a hand on it.

Then just two minutes later, Xherdan Shaqiri billowed a beautiful leftie cross into the box and Wijnaldum rose beautifully and thumped a stunning header into the back of the net. From 1-0 to 3-0 in the blink of an eye, Wijnaldum's three-minute warning turned the tide.
4. Coutinho's Final DisgracePhilippe Coutinho lost his place in the Barcelona side over the winter and looked for all the world like he was incapable of winning it back on his own merit. Whenever he was given the chance to play, he was terrible.
Then Ousmane Dembélé, the man who had taken his place, picked up a hamstring injury. This was his chance now! And to be fair to him he… didn't take it. Oh sure, he kept his place in the side but that was only because there was no other option.

The Liverpool tie offered him a chance for redemption, a chance to play Premier League opposition (the kind he always thrived against). His old club, no less! He was bright in spells in the first leg but faded as his Baby Lungs gave out.
In the second leg, however? He was absolutely terrible. No passes of substance, no runs, dispossessed easily and one weak shot which didn't trouble Alisson. He was hauled off on the hour for Nelson Semedo, his humiliation complete. It's hard to see any way back for him now. Sell him for a pack of crisps and some Lucozade. The biggest flop of all-time.
5. Divock of DestinyDivock Origi was a joke. An afterthought. Liverpool had signed top-class forwards and he was relegated to the bench.

They loaned him out, then tried to sell him. No one would pay up so he stayed, a bit of depth? Why not. He'd never play. Except in their greatest moments of desperation, Jurgen Klopp turned to him and he answered the call.
First, against Everton. Second, against Newcastle. Late goals, late winners to keep a league title challenge alive every time it looked like faltering. Third, against Barcelona. Salah out. Firmino out. There's no way they can go through. But Origi was Johnny-on-the-spot yet again.

Stabbed home a rebound to open the scoring and thumped home Trent Alexander-Arnold's genius to end the scoring.
The Belgian bookended the night with goals that had a touch of destiny about them.
And with Alisson being the man in goal for both of Barcelona's Champions League capitulations and Divock Origi constantly showing up at the death like the Riders of Rohan, turning the tide of battle Liverpool's way, you'd be a f00l to bet against them in Madrid.