(after extra-time - Liverpool win 4-3 on penalties)
Florent Sinama Pongolle was the hero for Liverpool as a Reds reserve team knocked out a full-strength Spurs side in a penalty shoot-out.
The hosts looked destined for an extra-time victory when Jermain Defoe, who had come off the bench, swept home Frederic Kanoute's 108th-minute cross.
But in the 117th minute Kanoute handled and Pongolle scored the penalty which made it 1-1 and forced a shoot-out.
Kanoute and Michael Brown missed and Pongolle scored again to win it.
Spurs had much the more experienced line-up - only Defoe was left out from their full-strength side - and they gave the Liverpool youngsters early warning of their intentions when Kanoute rifled a shot against the bar.
Liverpool boss Rafael Benitez, who places a low priority on the Carling Cup, saw his reserve team constantly forced on to the back foot by Spurs in the opening half.
Reto Ziegler came close twice but Rohan Ricketts, recalled by Martin Jol after a loan spell at Coventry, was next to really threaten the Liverpool goal as he headed wide from Kanoute's cross while totally unmarked.
In the 37th minute Robbie Keane had a good opportunity, as Tottenham continued to dominate, but Jerzy Dudek blocked it and then a Ziegler cross was headed by Kanoute into the path of Keane, whose effort scraped the outside of the post.
In the 59th minute Keane, after again linking up with Kanoute, saw his volley kept out by a world-class Dudek save.
Tottenham's supporters were becoming impatient as their heroes enjoyed the vast share of possession against the Reds reserves, without breaking the deadlock.
Their mood was lifted when Defoe, with 10 goals to his name before this game, was sent on from the bench as Spurs switched to a three-pronged strikeforce.
But it was Liverpool's youngsters who finished the opening 90 minutes strongest - as Florent Sinama Pongolle began to grow in confidence.
In the 77th minute Pongolle was put through clear on goal but was hauled down by Anthony Gardner, who was inexplicably shown a yellow card rather than red, and then the striker set up substitute John Welsh whose shot was close.
Spurs boss Jol tweaked his system again, withdrawing Keane to return a 4-4-2, but at the start of extra-time Liverpool again threatened, as Welsh's 95th-minute shot beat England goalkeeper Paul Robinson but not the post.
But with Defoe around, Spurs were always a threat too and the England striker came close either side of extra-time half-time - once thwarted by young defender David Raven and then seeing his shot whistle past the upright.
Then finally, in the 108th minute, Spurs broke the deadlock as Kanoute sprung the offside trap to gallop down the left before squaring towards Defoe who swept home with a clinical finish.
Spurs had one foot in the semi-finals, but after Robinson brilliantly kept out a Pongolle shot, the same Liverpool player took the corner and Kanoute handled it in full view of the referee.
A penalty was given and, with three minutes of extra-time left, Pongolle took it himself to send the game towards the penalty shoot-out.
Defoe went first for Spurs and scored, Stephane Henchoz stepped up for Liverpool and scored and then Michael Carrick and Richie Partridge made it two apiece.
Kanoute, the villain for Spurs when he conceded the penalty in extra-time, had his kick saved by Dudek and Robinson then pulled off a save to deny Darren Potter.
Michael Brown went next for Tottenham but blasted over and when Welsh hammered his kick home, that left Ziegler needing to score to keep his side in it, and the Swiss teenager kept his nerve.
But Pongolle, taking the fifth Reds spot-kick, needed to score to put his team in the last four and he held his nerve to put Spurs out.
Tottenham: Robinson, Pamarot, Gardner, King, Atouba, Ricketts (Defoe 66), Brown, Carrick, Ziegler, Kanoute, Keane (Pedro Mendes 85).
Subs Not Used: Fulop, Naybet, Redknapp.
Booked: Pamarot, Gardner.
Goals: Defoe 108.
Liverpool: Dudek, Raven, Henchoz, Whitbread, Warnock, Nunez (Smyth 70), Diao (Partridge 111), Biscan, Potter, Mellor (Welsh 52), Sinama Pongolle.
Subs Not Used: Kirkland, Foy.
Goals: Sinama Pongolle 117 pen.
Ref: N Barry (N Lincolnshire).