Even by Tranmere Rovers' standards this was utterly remarkable. Trailing by three goals at the interval, John Aldridge's team of journeymen and honest triers produced the most astonishing of comebacks to move into the quarter-finals of the FA Cup where they will play host to Liverpool.
The heroes were Paul Rideout, who claimed a sublime hat-trick, and Stuart Barlow, who scrambled home the winning goal with just seven minutes remaining.
Southampton became the seventh Premiership club in 18 months to be bundled out of one of the major cup tournaments by the Wirral club.
Southampton were so vastly superior in the early stages that, had their finishing matched their highly diligent approach play, the game, as a competition, would have been pronounced dead long before the interval after goals from Hassan Kachloul, Chris Marsden and Dean Richards.
TRANMERE ROVERS: Achterberg; Allen, Jobson, Challinor (Barlow, 45); Hinds, Flynn, Hamilton (Henry, 45), Koumas, Yates; Rideout, Parkinson.
SOUTHAMPTON: Jones: Gibbens, Lundekvam, Richards, Bridge; Pahars (Bleidelis, 45), Marsden, Draper, Tessem; Beattie, Kachloul.
Referee: S Dunn