Saints were dumped out of the FA Youth Cup as they were beaten 3-1 by Charlton at St Mary’s.
Jason Dodd’s side had made it through to the fourth round with a 7-0 demolition of Portsmouth.
But without the hat-trick hero of that day, Sam Gallagher, who was out of contention after starting for the first team against Arsenal on Tuesday night, they were beaten by the under-18 side of their Championship rivals.
Saints got off to the worst possible start as they fell behind after just three minutes.
It was a nasty one to concede too, as it came direct from a left footed inswinging corner from the right taken by Charlton captain Tareiq Holmes-Dennis.
The ball was dropping under the crossbar of Harry Isted who looked to have the situation under control, but under pressure from Karlan Ahearn-Grant he fumbled the ball and the grateful Addicks midfielder turned it home from a yard out.
Saints regained their composure and created some decent chances when they were able to break out of the scrappy midfield battle during the first half, but were not able to apply the finishing touch.
Josh Sims was always a major threat cutting in from the left.
He laid on shooting opportunities for Jake Flannigan who fired wide from the edge of the area and, most notably, Jake Hesketh, who really should have scored with time to take a touch and then shoot just ten yards out.
Hesketh twice tried his luck midway through the half but missed the target while Charlton were similarly stymied in the final third.
Holmes-Dennis shot wide while Brandon Hanlan and Levander Pyke both picked out Isted with well struck efforts.
Saints started the second period looking to take the game to Charlton and were piling the pressure on their visitors.
Sims again cut in and shot, Flannigan got in a header and Saints fired goalwards after winning a free kick inside the area for a backpass but all three efforts were blocked by keeper Harry Doherty.
However, after Isted had kept Saints in the tie with a fine save down to his left to deny Hanlan, the home side’s persistence paid off and they equalised on 67 minutes.
Flannigan created the chance with his industry, winning possession of the ball in the middle of the Charlton half.
He found Hesketh who delivered what he had been threatening for most of the evening as he cut inside and from 20 yards struck a low shot that beat Doherty diving to his left and found the bottom corner.
Even Charlton seemed to sense they might need to hold tight to stay in the match, but things quickly swung in their favour as they scored twice in the space of just a minute.
They retook the lead on 73 minutes as Regan Cook broke from deep, fed the ball out to the right to Ahearn-Grant and continued his run into the area. He was picked out by his teammate and steered the ball home first time.
Just 20 seconds after the restart it was 3-1.
Saints quickly lost possession after the kick-off and before they knew what had hit them, Holmes-Dennis’ shot from distance cannoned into Joshua Umerah who was in the area with his back to goal.
He was allowed to spin outside and quickly got off a shot that beat Isted and left Saints struggling to get back into the tie.
It was something they couldn’t manage and the prospect of a tasty fifth round home tie against Arsenal bit the dust as they were knocked out.
Saints: Isted, Leggett, McCarthy, Debayo, Nehemie (Wood 75), Mason (Little 80), Flannigan, Irvine (Seager 61), Hesketh, Sims, Barnes.
Charlton: Doherty, Barnes, Pyke, Gomez, Thomas, Holmes-Dennis, Cook, Edwards, Umerah, Hanlan (Lapslie 90), Ahearne-Grant (Kennedy 83).