Nineteen years on from the unforgettable miracle of Istanbul in the 2004-05 final, the Reds were once again forced to do it the hard way against the Rossoneri, albeit not quite to that degree.
Ibrahima Konate, Virgil van Dijk and Dominik Szoboszlai all cancelled out Christian Pulisic's 167-second opener on a chastening evening for Milan, who also lost goalkeeper Mike Maignan to injury at the start of the second half.
Fresh from demolishing Venezia 4-0 in the weekend's Serie A contest, Milan raced out of the blocks in front of the home crowd, who were in delirium just three minutes in as Pulisic charged at an exposed backline and finished into the far corner.
However, the Rossoneri were found wanting at set-pieces, as Konate levelled from a free kick before Van Dijk also towered above the red and black jerseys to nod in goal number two for Liverpool.
Maignan did not cover himself in glory on either occasion, and the Frenchman was clearly uncomfortable towards the end of the first half, before having to call it a day early in the second as a clash with Diogo Jota left him writhing in agony.
With 19-year-old Lorenzo Torriani in between the posts, Milan failed to keep Liverpool at bay again, and the die was cast when Szoboszlai's improvised thigh finish sealed the deal for the redeemed Reds.
MILAN VS. LIVERPOOL HIGHLIGHTS
Christian Pulisic goal vs. Liverpool (3rd min, Milan 1-0 Liverpool)
This was not in the script for Slot! The Rossoneri take the lead after just 187 seconds, and Kostas Tsimikas in particular will not want to look back on this one.
The left-back - who replaced Andrew Robertson tonight - is caught out of position high up the field, allowing Pulisic to charge down the right unchallenged, and the American has the finish to match, smashing the ball into the far side of the net.
Ibrahima Konate goal vs. Milan (24th min, Milan 1-1 Liverpool)
A Liverpool defender may not have covered himself in glory for Pulisic's early opener, but two of them combine to bring the visitors back on level terms.
Trent Alexander-Arnold lines up a free kick on the left-hand side and whips the ball into a packed penalty area, right on the money for Konate.
Mike Maignan comes off his line and tries to punch clear, but the Frenchman misses, allowing his compatriot to nod the ball into an empty net!
Virgil van Dijk goal vs. Milan (41st min, Milan 1-2 Liverpool)
Another Liverpool comeback against Milan? I feel like I have seen this movie somewhere before...
Another set-piece does the damage for Slot's men, and it is Tsimikas at the left corner flag making up for his earlier misdemeanour, sending in a brilliant delivery that Van Dijk nods into the back of the net.
Dominik Szoboszlai goal vs. Milan (67th min, Milan 1-3 Liverpool)
No need for another Istanbul-esque miracle this time, as the visitors surely seal an opening maximum with a quarter of the game remaining.
Cody Gakpo breezes past Strahinja Pavlovic into the left-hand side of the box, and his cutback is on the money for Szoboszlai to notch Liverpool's third with an improvised finish off of his thigh.
MAN OF THE MATCH - IBRAHIMA KONATE
Scorer of the goal that sparked the Liverpool comeback, Konate ruthlessly delivered from Alexander-Arnold's set-piece and also played his part defensively to ensure that Milan would not be the ones to peg it back to 3-3 this time.
The Frenchman made five clearances and also shone with the ball at his feet, completing four of his five long passes and registering a total accuracy of 93%.
MILAN VS. LIVERPOOL MATCH STATS
Possession: Milan 49%-51% Liverpool
Shots: Milan 8-23 Liverpool
Shots on target: Milan 2-11 Liverpool
Corners: Milan 2-5 Liverpool
Fouls: Milan 9-12 Liverpool
BEST STATS
WHAT NEXT?
The Premier League is back on the menu for Liverpool this weekend, as the Reds host Bournemouth at Anfield on Saturday before taking on West Ham United in the EFL Cup next Wednesday.
As for Milan, Tuesday's loss is a significant setback ahead of Sunday's derby with San Siro rivals Inter Milan.