Southampton's youngsters were well beaten by an experienced Southend United side in the Checkatrade Trophy, prompting their exit from the competition.
A hat-trick of quick fire strikes in the first half, two of Saints' own making, were decisive for the hosts, who progress alongside Cambridge United to the knockout phases.
Harry Bunn's 13th minute opener set the tone for the tie, after he was quickest to react to a spillage from Saints stopper Harry Lewis, and turn home from close range.
Six minutes later, midfielder Harry Kyprianou was the beneficiary of another goalmouth scramble, this time caused by a Stephen McLaughlin shot, who incidentally tried to claim the goal for himself.
Kyprianou eventually stabbed the ball over the line, giving the hosts a two goal cushion, before young full-back Elvis Bwomono rounded off a smart Southend move to net his career first - and Southend's third - of the evening in the 24th minute.
The defender linked well with fellow scorer Bunn, before firing across Lewis and finding the far corner.
Radhi Jaïdi made a double switch at the break, in an attempt to change the flow of the tie. And momentarily, it did.
The visitors had a brief spell of pressure in the second period, culminating in a presentable chance for Marcus Barnes and Jonathan Afolabi, who were both inches away from latching onto a searching Yan Valery cross from the right.
The game had ultimately escaped Saints during an uncharacteristic first half, though, and despite rallying to produce a more controlled second 45 minutes, the three goal deficit was too hefty to chase down.
Nathan Bishop (GK)
Luke HyamTimothee Dieng (73′)
Dru Yearwood (C)Jason Demetriou (82′)
Harry BunnCharlie Kelman (85′)
Tom O'Connor (C)
Christoph KlarerKayne Ramsay (45′)
Nathan TellaHarry Hamblin (45′)