Andy Thorn pounced on an extra-time miskick by Liverpool captain Steve Nicol to earn relegation strugglers Crystal Palace a home Coca-Cola Cup quarter-final against Chelsea.
The second leg of London's replay double win over Merseyside was an amazing tactical triumph for manager Steve Coppell, who had 13 players on the injury list, yet pulled out a plum in teenager Grant Watts. The 19-year-old YTS trainee switched on an electrifying debut and headed Palace ahead after 15 minutes.
Though they were pegged back by a penalty decision by Clacton referee Peter Foakes, that left everyone all at sea, they bravely kept plugging away.
And when Nicol sliced his attempted clearance of a John Humphrey cross high into his own penalty area, defender Thorn won the race to head past a hesitant Mike Hooper.
It was the first goal of the season for the former Wimbledon defender, who wrestled an FA Cup Winners' medal from Liverpool in the 1988 final. He was also on the winning Palace side in the famous 1990 semi-final win over the Reds at Villa Park.
But they still had to survive a cracking half-volley against the bar from Jamie Redknapp before completing the defeat of the four-times winners.
Without a recognised striker, Coppell was expected to gamble on the versatile Eddie McGoldrick at centre-forward. Instead he asked him to play as sweeper, a role he performed majestically. Up front, he teamed Croydon born striker Watts, who had scored eight goals for the reserves with Simon Rodger, recalled after damaging knee ligaments in the first game of the season.
The gamble quickly paid off when Watts opened his senior account. Nicol, moved to centre-half to cover for sick Liverpool captain Mark Wright, had almost driven a clearance under his own crossbar and from Rodger's corner, Andy Thorn flicked on into the middle and Watts scored with a downward header - despite Liverpool claims that Hooper stopped the ball on the line.
He thought he had got a second from an identical move in the 51st minute, but this time Rob Jones was well positioned on the line and turned his header against the underside of the crossbar.
By then they had pulled level with a hotly-disputed 26th minute penalty. Few in the crowd saw a clear fowl, but the linesman flagged the moment Paul Stewart went down as a melee converged on Redknapp's low cross from the right.
Foakes pointed to the spot, for Mike Marsh to convert confidently, the full-back's fourth goal in seven matches.
Mark Walters, starting after Sunday's double against Blackburn, volleyed against the bar and Nigel Martyn saved raggedly from the one-time England winger as Liverpool began to dominate.
But Palace regained their composure and held them off in the second half with only a 79th minute scare, when Martyn spilled a low shot from substitute Ronnie Rosenthal, but recovered to block Walters' follow-up.
Palace had their chance to avoid extra-time three minutes later when Southgate headed over at the far post from Rodgers' cross.
Thorn did not miss in extra-time and though it took a desperate rearguard to hold on to their advantage, but Palace did it to win against the odds. Coppell said: "Defensively, each and every player more than earned his money tonight, in an age of cut-backs! After the first 15 minutes, I felt we had a chance. The attitude was right, we seemed to understand what we were doing. The feeling we could win just grew. It's a night for us all to enjoy after all the stuff we've suffered this year."
Thorn was completing a hat-trick of cup upsets over Liverpool, following Wimbledon's 1988 final triumph and Palace's famous 4-3 semi-final win at Villa Park. He said: "I've got a good personal record against them but it was the youngsters who deserved the praise. We were a bit lightweight but everyone did the job they were asked to."
Palace's 1-1 draw at Anfield in the first game earned fierce criticism from Liverpool manager Graeme Souness. But Souness reserved his anger this time for his own players, accusing them of 'pretty football'. He said: "We had the majority of possession but you've got to turn that into goals and we didn't. What we're doing is having lots of possession with pretty football but not hurting teams."
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