Shane Long struck a stoppage-time winner as Southampton upset Liverpool 1-0 at Anfield on Wednesday to reach the League Cup final with a 2-0 aggregate victory in their last-four clash.
Liverpool laid siege to Southampton's goal in the second half having been outplayed in the opening 45 minutes, but the visitors were doggedly determined to keep the hosts at bay and poached a winner at the death.
Southampton had chances to put the tie to bed in the first half, with Dusan Tadic and Steven Davis guilty of poor finishing, but after the break it was all Liverpool and Daniel Sturridge wasted two superb chances.
With the seconds ticking away, Liverpool felt they should have had a penalty when Divock Origi appeared to be tripped in the area, but Southampton broke swiftly and substitute Long blasted a shot past Loris Karius.
Southampton, who have sold millions of pounds worth of players to Liverpool in recent seasons, will face either Manchester United or Hull City in the final.
United will take a 2-0 lead into the semi-final second leg at Hull on Thursday.