Fifty-seven games into a gruelling season Liverpool could have crumbled when their 2-0 first-leg lead was wiped out before half-time by an inspired Villarreal playing to reach their first-ever Champions League final.
Instead, the Reds will be in European club football's showpiece occasion for the third time in five seasons after they hit back to win Tuesday's game 3-2 and progress from the semi-final 5-2 on aggregate.
"Before the game I told the boys that I would like to read the headlines that 'the mentality monsters were in town'," said beaming Liverpool manager Jurgen Klopp.
Six games now separate Klopp's men from an achievement never before achieved in English football -- winning all four major trophies on offer in the same season.
The League Cup is already in the trophy cabinet after Liverpool beat Chelsea on penalties in the final in February, with a rematch of that game to come in the FA Cup final on May 14.
Liverpool's Premier League title hopes still depend on Manchester City, who hold a one-point lead at the top of the table with four games to go.
And the two teams that have dominated English football over the past five years could face off on the biggest stage of all if City see off Real Madrid in Wednesday's other semi-final.
The biggest surprise was that there was ever any doubt about Liverpool's safe passage to Paris on May 28.
In 28 games in 2022 prior to Tuesday's match in Spain, Klopp's men had trailed for a total of 53 minutes.
But for just short of an hour they were behind at the Estadio de la Ceramica as David threatened to slay Goliath thanks to first-half goals from Boulaye Dia and Francis Coquelin.
- Diaz to the rescue -
However, the vast gulf in resources between the clubs showed when Klopp could unleash £50 million ($63 million) January signing Luis Diaz at the break.
The Colombian, together with some generous goalkeeping from Villarreal stopper Geronimo Rulli, turned the game back in Liverpool's favour as Fabinho, Diaz and Sadio Mane scored three goals in 12 minutes.
"He’s a special, special player," said Andy Robertson of Diaz. "The talent he has, the will he has to win. he fits us perfectly. He made a big difference."
Liverpool's rich tradition in the European Cup was born in the 1970s and 1980s, when they won the trophy four times as the dominant force in the English game.
They won it again under Rafael Benitez in 2005, famously coming back from 3-0 down to beat AC Milan on penalties and Klopp's side beat Tottenham in the 2019 final.
Victory at the Stade de France would move them alongside AC Milan as the second most successful club in the competition's history, with seven titles.
Such a landmark seemed an impossible dream when Klopp arrived at Anfield in 2015.
Liverpool had reached the Champions League final twice in three decades and had not won a domestic league title since 1990.
But the former Borussia Dortmund boss has transformed a sleeping giant into a modern great of European football.
"It feels like it's the first (final) to be honest, because it is always so special," said Klopp. "It is, for me, the best club competition in the world. I love it, love the sound, love the nights, everything.
"With the 500 games, like it feels, that the boys played it is completely normal that the first half can happen but reacting like we reacted made it really special again and it is that that we are really happy about."
Klopp's fourth Champions League final matches the current record for a coach set by the late Miguel Munoz, Marcelo Lippi, Alex Ferguson and Carlo Ancelotti.
Pep Guardiola could join that list if City make it to Paris, while Ancelotti will hold the record on his own should 13-time winners Madrid overcome a 4-3 first-leg deficit.
"Whoever it will be, it will be massive," said Klopp.
It will certainly take a huge effort to deny Liverpool a seventh European crown.