Brighton dumped holders Liverpool out of the FA Cup thanks to a brilliant 92nd minute winner from Kaoru Mitoma as the Seagulls ran out deserved 2-1 victors to earn progression to the fifth round of the competition.
The hosts, as expected, were without wantaway midfielder Moises Caicedo, who went public with his desire to leave after Arsenal had a £60m bid rejected on Friday. "We are ready to go forward without him," manager Roberto De Zerbi said post-match. "If we don't lose Caicedo we are ready to fight for Europe," he added.
The Reds went ahead when Mo Salah carved through the heart of the Brighton defence, highlighting Caicedo's obvious absence, to find the intelligent run of Harvey Elliott, who squirmed the ball beneath an onrushing Jason Steele (30).
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Brighton responded valiantly, restoring parity nine minutes later when Tariq Lamptey's long-range effort deflected fortuitously beyond a wrong-footed Allison via the boot of Lewis Dunk (39).
Jurgen Klopp attempted to force the issue midway through the second period, introducing James Milner, Jordan Henderson and Darwin Nunez, but spirited Brighton held firm, before firing the killer blow in second-half stoppage time.
Mitoma, outstanding all afternoon, had threatened Allison's goal on multiple occasions and was rewarded for his persistence in the dying embers of the game, shimmying through a crowd of players at the back post before rifling the winner into the roof of the net (90+2).
How majestic Mitoma inspired cup progression
The warning signs were there but they went unheeded by Liverpool's often lifeless backline.
Back at the scene of a 3-0 thumping a fortnight ago which Klopp described as the worst of his managerial career, the Reds were improved in patches, but powerless to prevent Mitoma's wonderful improvisation late on.
The Japanese international, who terrorised Trent Alexander-Arnold enough to warrant the full-back's withdrawal after just 59 minutes, had presented Solly March with the chance to tie up proceedings not long before his decisive strike.
A neat flick of the right boot found March on the move centrally, but he was met swiftly by the towering frame of Alisson, who sprawled to deny the winger before the rebound bounced the wrong side of the post.
March, incidentally, ended up in the back of the net - the ball did not.
Undeterred, Mitoma continued to wreak havoc down the right before getting the break his performance deserved - bamboozling Joe Gomez as he controlled Pervis Estupinan's lofted cross and lashed into the net.
The dramatic nature of the winner - which required VAR to check Estupinan was onside when diverting the ball back across goal - prompted an explosion of noise inside the Amex Stadium as fans sung the name of their hero, while a dejected Klopp watched on helplessly from the touchline, wincing awkwardly at another show of shoddy defending.
Liverpool have lost nine games in all competitions this term, more than twice as many defeats as in the whole of last season. "We will not fall apart, I can tell you...there were steps in the right direction," Klopp said afterwards.
The view from the winning dugout was actually less flattering with De Zerbi making it clear that he was not thrilled with his side's all-round performance, despite the outcome - a clear indication of Brighton's soaring trajectory.
De Zerbi: Ready to go forward without Caicedo
Brighton manager Roberto De Zerbi:
"This was a different team to the last game. It was very difficult to win this game and we are very happy. If you ask about the quality I didn't like the game, we can improve a lot. We made too many simple mistakes.
"We have to work. Most important in football is to have heart and balls, you understand? To become a great team you have to win this game. We didn't play so well like the last game [against Liverpool].
"You think it's very nice today because we won the game, but to become bigger we have to understand the game. The result is important but the performance also.
"We are not like Manchester City, Man United, Arsenal, Tottenham or Liverpool and Chelsea. We are not the same level. But we want to fight to improve. In the moment we are playing well. In the table we stay in sixth.
On Caicedo he added: "It is difficult for me to be a coach. To be a coach and chairman is more difficult. Caicedo is a good guy. I would like him to finish the season with us. But we are ready to go forward without him.
"We've lost [Leandro] Trossard. If we lose also Caicedo that's a problem for us. If we want to fight for Europe or the maximum we can get - I don't like this."
Klopp: We will not fall apart
Liverpool manager Jurgen Klopp:
"We had our moments again. We make steps but we have to improve. You have to respect what they do, it's really good. There were steps in the right direction, we have to go from there.
"We have to build. Body language I was not happy with. Last game here we couldn't have won, but this today nobody would be surprised if we had won.
"We will not fall apart, I can tell you. If it looks like that I'm sorry. It's not that we were falling apart late on it was frustration - players get yellow cards, that happens.
"After we came back from the World Cup break we wanted to go for it. So far it didn't happen properly. But it just means we have to keep working. Some very good performances today.
"I'm not over the moon about this performance overall. But this was much better, two weeks ago was horrendous. I understand 100 per cent when people say we aren't happy with the game. I'm sorry for Liverpool fans - today we paid a little bit back. But we are still out and that's the worst outcome from the game."
Analysis: Buoyant Brighton on the up
Sky Sports' Laura Hunter:
Liverpool must be sick of the sight of Brighton - and they aren't the only side to have developed a distaste. The Seagulls have outclassed many visitors to the Amex this season, but none more so than under-fire Liverpool.
Roberto De Zerbi's side have scored eight goals across three encounters with the Reds. It wasn't quite the demolition that unfolded on the south coast in mid-January - a performance Klopp described as "horrendous" - but the defending at times was just as disastrous.
Klopp insisted pre-match that he has not become a "bad manager overnight" and he can solve Liverpool's current malaise, but the Amex is a difficult place to go soul searching - as proved.
De Zerbi has got this courageous Brighton team running like clockwork and with genuine belief they can match any side. Not even the loss of key midfielder Moises Caicedo disrupted their rhythm.
The Italian was critical of his side in the aftermath of the game, perhaps unfairly, but such high expectations speak to the club's rising ambition and broader trajectory. "If you ask about the quality I didn't like the game, we can improve a lot," he said. Two wins over Liverpool in the space of 15 days is, however, testament to their growth under the Italian.
Many questioned whether Brighton could continue to show signs of improvement after Graham Potter swapped Brighton for Chelsea in September. Such concerns should now be duly laid to rest.
What's next?
Brighton's next game is at home to Bournemouth in the Premier League on Saturday; kick-off 3pm.
The Seagulls then travel to Selhurst Park to take on rivals Crystal Palace on Saturday February 11; kick-off 3pm.
Liverpool's next game is also in the Premier League, with a trip to Wolves on Saturday; kick-off 3pm.
Jurgen Klopp's side then travel to bitter rivals Everton on February 13 for a Monday Night Football encounter, live on Sky Sports; kick-off 8pm.