Liverpool flirted with disaster against Villarreal on Tuesday before scoring three goals in 12 minutes to reach the Champions League final with a 3-2 comeback win in Spain and keep their bid for four season titles alive.
Boulaye Dia put Villarreal ahead three minutes into the game and the hosts made it 2-0 in the 41st from Francis Coquelin to cancel out their 2-0 defeat in the first-leg semi last week at Anfield.
But Liverpool regrouped and reached a third final in five years 5-2 on aggregate from goals by Fabinho in the 62nd, substitute Luis Diaz in the 67th and Sadio Mane in the 74th to progress 5-2 on aggregate.
The frustration of Europa League champions Villarreal, who had upset Juventus and Bayern Munich in the previous rounds, was complete when Etienne Capoue was sent off for a second bookable offence late in the game.
Liverpool will be bidding for a seventh title in the elite event on May 28 in Paris where they will face record winners Real Madrid or English rivals Manchester City.
City take a slender 4-3 lead into their second leg on Wednesday at the Bernabeu against the freshly crowned Spanish champions.
Jürgen Klopp's Liverpool have already won the League Cup, are in the FA Cup final against Chelsea later this month and one point behind City in the Premier League. No English team has ever achieved the quadruple.
"It was very difficult. They played very well in the first half. We regrouped at half-time, grabbed the game by the scruff of the neck and got the result we needed," Liverpool full-back Trent Alexander-Arnold told BT Sport.
Fabinho said: "It was a hard first half for us, maybe the hardest of the season. But you have to be ready for everything and try to play football. After our first goal we controlled the game. That is it and we are in the final."
Coming off a poor showing in the first leg they could have easily lost by a bigger margin and in which they never seriously threatened, Villarreal were a changed team on Tuesday and the roles reversed.
Pervis Estupinan's cross found Capoue at the far post and he laid the ball back to Dia to slot into the empty net for a dream start three minutes into the game.
Liverpool were very much on the back foot and Villarreal screamed in vain for a penalty after contact between Giovani Lo Celso and goalkeeper Alisson Becker.
But they were able to rejoice shortly after when Coquelin surprised Alexander-Arnold to head home Capoue's cross for 2-0 in the 41st to level the tie.
Liverpool improved considerably after the break thanks to the introduction of Diaz and were close to scoring in the 55th when Alexander-Arnold's shot was deflected by Coquelin and looped over goalkeeper Geronimo Rulli on to the top of the crossbar.
Fabinho soothed their nerves in the 62nd when he got the ball back from Mohamed Salah and scored between Rulli's legs from a tight angle.
Liverpool were now in cruise control as Diaz nodded the 2-2 equalizer off Alexander-Arnold's cross in the 67th, and Mane ended any remaining doubts seven minutes later with the 3-2 winner into the empty net after rounding Rulli.