Stand-in striker Divock Origi and substitute Georginio Wijnaldum both scored twice as Lionel Messi’s side threw away a 3-0 first leg lead and crashed out at a frenzied Anfield.
The nature of Liverpool’s victory was quickly compared to the 2005 Champions League final in Istanbul when they came back from 3-0 down to beat AC Milan on penalties.
A season that threatened to end with Liverpool being pipped to the Premier League title by Manchester City this weekend and exiting the Champions League at the semi-final stage will now culminate in a final against either Ajax or Tottenham in Madrid on June 1 when they could become kings of Europe for a sixth time.
For Barcelona, the crushing defeat was the second consecutive year they had surrendered a commanding first-leg lead in this competition — and the scale of the capitulation leaves coach Ernesto Valverde facing the sack.
Liverpool went into the match deprived of two of their most potent attacking weapons in Mohamed Salah and Roberto Firmino due to injury.
However, Origi and Wijnaldum stepped up magnificently, leaving Klopp to marvel at his players in a joyous outburst laced with profanities.
“It’s 10 past 10, most of your children are probably in bed but these boys are f*****g talented giants. It’s unbelievable,” he told BT Sport.
“The whole game was too much. Winning is difficult but with a clean sheet, I don’t know how they did it.
“It means so much to all of us. There are more important things in the world. But creating this emotional atmosphere together is so special. It’s all about the players.
“It shows what’s possible in football. It’s so nice.”
Point to prove
Wijnaldum admitted he had been smarting at being forced to start on the bench and felt he had a point to prove.
“Once again we showed that everything is possible in football,” the Dutchman said. “I was really angry at the manager that he put me on the bench but I had to do something to help the team when I came on.
“We believe it from the start. People from outside (the club), they thought it was not possible, but we still managed to do this.”
Origi would almost certainly not have started the match had Salah — the Premier League’s top scorer this season with 22 goals — and Firmino been fit.
But the 24-year-old Belgian has made a habit of scoring important goals in Liverpool’s challenge for a first Premier League title in 29 years and he notched his first ever in the Champions League on seven minutes, pouncing on the rebound after Marc-Andre ter Stegen had denied Jordan Henderson’s initial effort.
Messi, who had dominated the first leg with two goals, had quickly and uncharacteristically been rattled by Liverpool defender Andy Robertson, wagging his finger in the Scotsman’s face.
Liverpool were seemingly dealt another injury blow as Robertson could not continue after half-time. But his replacement, Wijnaldum, was to have a dramatic impact.
Liverpool goalkeeper Alisson Becker made an important save from Luis Suarez before Wijnaldum sent Anfield into raptures twice in a matter of minutes.
Firstly, the Dutch midfielder was found by Trent Alexander-Arnold’s low cross and drilled under Ter Stegen.
And from Liverpool’s next attack, Xherdan Shaqiri picked out Wijnaldum to head home at the Kop end.
Valverde desperately tried to salvage the match, replacing former Liverpool player Philippe Coutinho with Nelson Semedo.
The change briefly had an impact, but a sluggish Barca were made to look foolish when they were caught napping by a quickly-taken Alexander-Arnold corner that picked out Origi completely unmarked to fire high into the net, sparking extraordinary celebrations.
“There have been glorious, entirely improbable games in Liverpool’s European history, including the mind-bending highs of Istanbul,” the Guardian newspaper said. “But this was something else, an effort of will that, frankly, took the breath away.”
And while Liverpool are dreaming of also grabbing the Premier League title this weekend, Valverde’s future could be bleak.
“I do not know how it’s going to affect me,” Valverde said. “But here we are, the coach has to take responsibility.”
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